JP4357435B2 - Photothermographic material and image forming method thereof - Google Patents

Abstract

A photothermographic material wherein at least an image-forming layer on at least one surface of a support, the image-forming layer containing a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent, and a binder, wherein, an outermost layer is provided as a layer most remote from the support on the side of the support where the image-forming layer is provided, a non-photosensitive intermediate layer A containing a binder and provided in adjacent with the image-forming layer and between the imag-forming layer and the outermost layer, wherein the binder of the non-photosensitive intermediate layer A contains 80 % by mass or more of a polymer formed by copolymerizing a monomer represented by Formula (M), a non-photosensitive intermediate layer B containing a binder and provided between the non-photosensitive intermediate layer A and the outermost layer, and the binder of the non-photosensitive intermediate layer B contains 50 % by mass or more of a hydrophilic polymer derived from animal protein: Formula (M) CH2=CR<01>-CR<02>=CH2, as well as image forming method thereof.

Description

  The present invention relates to a photothermographic material and an image forming method thereof.

  In recent years, in the medical field, reduction of waste processing liquid has been strongly desired from the viewpoint of environmental protection and space saving. Therefore, photosensitive thermal development for medical diagnosis and photographic technology that can be efficiently exposed by a laser image setter or laser imager and can form a clear black image having high resolution and sharpness. There is a need for technology relating to photographic materials. These photosensitive photothermographic materials can eliminate the use of solution processing chemicals and supply customers with a simpler heat development processing system that does not damage the environment.

  Although there is a similar requirement in the field of general image forming materials, medical images are required to have high image quality with excellent sharpness and graininess because they are required to be finely drawn, and are cooled from the viewpoint of ease of diagnosis. There is a feature that a black tone image is preferred. At present, various hard copy systems using pigments and dyes such as inkjet printers and electrophotography are distributed as general image forming systems. However, there is no satisfactory output system for medical images.

  On the other hand, thermal imaging systems using organic silver salts are described in many documents. In particular, the photothermographic material generally contains a catalytically active amount of a photocatalyst (eg, silver halide), a reducing agent, a reducible silver salt (eg, an organic silver salt), and a color tone that controls the color tone of silver if necessary. And an image forming layer dispersed in a binder matrix. The photothermographic material is heated to a high temperature (for example, 80 ° C. or higher) after image exposure, and is blackened by an oxidation-reduction reaction between silver halide or a reducible silver salt (functioning as an oxidizing agent) and a reducing agent. Form a silver image. The oxidation-reduction reaction is promoted by the catalytic action of the latent image of silver halide generated by exposure. Therefore, a black silver image is formed in the exposure area. Fuji Medical Dry Imager FM-DPL was released as a medical image forming system using a photothermographic material.

The photothermographic material contains the above-mentioned components, and all these components remain after development, so that there are many problems regarding storage stability. Methods that have been frequently studied in the past to solve the problem include changing the composition contained in the image forming layer and adding a new compound. For example, the printout property is improved by changing the silver halide to one having a high silver iodide content (see, for example, Patent Document 1 and Patent Document 2), or the occurrence of fogging by adding a polyhalogen compound. Various methods such as suppression (for example, see Patent Document 3) and increasing the content of silver behenate in the non-photosensitive organic silver salt (for example, see Patent Document 4) have been studied and achieved results. It's getting on.
Since the image forming layer is a direct part for forming an image, it is extremely important to examine the composition in the image forming layer as a method for improving storage stability. However, since these compositions are present in a mixture in the image forming layer, the sensitivity tends to be low when it is attempted to improve the storage stability, and the image density tends to be low when the generation of fog is suppressed. is there. It is extremely difficult to simultaneously achieve the contradictory performances of storage stability and high sensitivity, fog suppression and image density.
As described above, the photothermographic material is prepared in a well-balanced manner so as to maximize the advantages of each composition, and the storage stability is improved by simply changing or adding one composition. It ’s difficult. A method for improving storage stability without offsetting the characteristics of individual compositions is routinely eagerly desired.
JP-A-8-297345 Japanese Patent No. 2785129 JP 2001-312027 A JP 2000-7683 A

  Accordingly, an object of the present invention is to provide a photothermographic material excellent in image storability (raw storability) of an unexposed photosensitive material and image storability after exposure, and to provide an image forming method thereof.

The object of the present invention has been achieved by the following photothermographic material and image forming method.
<1> A photothermographic material comprising an image forming layer containing at least a photosensitive silver halide, a non-photosensitive organic acid silver salt, a reducing agent, and a binder on at least one surface side of a support. And
In the surface on which the image forming layer is provided on the support, an outermost layer is provided on the side farthest from the support,
A non-photosensitive intermediate layer A is provided between the image forming layer and the outermost layer adjacent to the image forming layer, and the binder of the non-photosensitive intermediate layer A is represented by the following general formula (M) Containing 80% by mass or more of a copolymer obtained by copolymerizing the monomer represented by
A non-photosensitive intermediate layer B is provided between the non-photosensitive intermediate layer A and the outermost layer,
The photothermographic material, wherein 50% by mass or more of at least one binder of the outermost layer and the non-photosensitive intermediate layer B is a hydrophilic polymer derived from animal protein:
Formula ^{_{(M) CH 2 = CR 01}} -CR 02 = CH 2
(Wherein R ⁰¹ and R ⁰² represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a halogen atom or a cyano group).
<2> The polymer obtained by copolymerizing the monomer represented by the general formula (M) is a polymer obtained by copolymerizing the monomer represented by the general formula (M) at 10% by mass or more and 70% by mass or less. <2> The photothermographic material according to <1>.
<3> The polymer obtained by copolymerizing the monomer represented by the general formula (M) is a polymer obtained by copolymerizing the monomer represented by the general formula (M) at 20% by mass or more and 40% by mass or less. <2> The photothermographic material according to <1> or <2>.

<4> The binder of the non-photosensitive intermediate layer B contains 50% by mass or more of a hydrophilic polymer derived from animal protein, and the binder of the outermost layer contains a latex of a hydrophobic polymer. The photothermographic material according to any one of <1> to <3>.
<5> The non-photosensitive intermediate layer B comprises two or more layers, and the non-photosensitive intermediate layer B on the side close to the non-photosensitive intermediate layer A contains 50% by mass or more of a hydrophilic polymer not derived from animal protein. <1> to <3, wherein the non-photosensitive intermediate layer B on the side close to the outermost layer contains a binder containing 50% by mass or more of a hydrophilic polymer derived from animal protein. The photothermographic material according to any one of the above.
<6> The photothermographic material according to <5>, wherein the outermost binder contains a hydrophilic polymer derived from an animal protein.
<7> The photothermographic material according to <5>, wherein the outermost layer binder contains a latex of a hydrophobic polymer.
<8> The photothermographic material according to <5>, wherein the outermost binder contains a hydrophilic polymer derived from animal protein and a latex of a hydrophobic polymer.

<9> The photothermographic material according to any one of <1> to <8>, wherein the reducing agent is a compound represented by the following general formula (R1).

(In the formula, R ¹¹ and R ¹¹ ′ each independently represent a secondary or tertiary alkyl group having 1 to 15 carbon atoms. R ¹² and R ¹² ′ are each independently substituted with a hydrogen atom or a benzene ring. .L representing the possible substituents, -S- group, or -CHR ¹³ - .R ¹³ representing the group, .X ¹ and X ¹ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms' is Each independently represents a hydrogen atom or a group that can be substituted on the benzene ring.)
<10> The photothermographic material according to any one of <1> to <9>, wherein the image forming layer further contains a development accelerator.
<11> The photothermographic material according to <9> or <10>, wherein the image forming layer further contains a compound represented by the following general formula (D).

(Wherein R ²¹ to R ²³ each independently represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group or a heterocyclic group)
<12> The photothermographic material according to any one of <1> to <11>, wherein the image forming layer further contains a compound represented by the following general formula (H).
General formula (H)
Q- (Y) n-C (Z ₁ ) (Z ₂ ) X
In the formula, Q represents an alkyl group, an aryl group, or a heterocyclic group. Y represents a divalent linking group. n represents 0-1. Z ₁ and Z ₂ each independently represent a halogen atom. X represents a hydrogen atom or an electron withdrawing group.
<13> The photothermographic material according to <12>, wherein the image forming layer contains two or more compounds represented by the general formula (H).

<14> The photothermographic material according to any one of <1> to <13>, wherein the image forming layer) further contains a compound represented by the following general formula (I).

In the formula (I), R represents a hydrogen atom or a substituent. m represents an integer of 1 to 6.
<15> The photothermographic material according to <14>, wherein the image forming layer further contains a color tone adjusting agent.
<16> The photothermographic material according to any one of <1> to <15>, wherein the non-photosensitive organic acid silver salt contains 90 mol% or more of silver behenate.
<17> The photothermographic material according to any one of <1> to <16>, wherein the coated silver amount is 1.3 g / m ² or less.
<18> The material according to any one of <1> to <17>, wherein any layer on the surface side on which the image forming layer is provided with respect to the support contains a crosslinking agent. Photothermographic material.
<19> An image forming method of a photothermographic material having an image exposure step and a heat development step, wherein in the heat development step, the photothermographic material according to any one of <1> to <18>. An image forming method of a photothermographic material, wherein the image is heated in 16 seconds or less.
<20> An image forming method of a photothermographic material having an image exposure step and a heat development step, wherein in the heat development step, the photothermographic material according to any one of <1> to <18>. An image forming method for a photothermographic material, wherein the photothermographic material is conveyed at a speed of 23 mm / sec or more.
<21> In the heat development step, the photothermographic material according to any one of <1> to <18> is conveyed at a speed of 23 mm / sec or more. An image forming method for a photothermographic material.

Usually, to improve the storage stability, the composition of the image forming layer is changed. However, if the composition of the image-forming layer is changed, adjustment with other compositions is extremely complicated, and every time a new composition developed is applied to the image-forming layer, all the compositions must be reviewed. I must. Further, the outermost layer is a portion that directly contacts the outside during development, transportation, storage, and the like, and problems other than image quality must be considered. For example, in order to improve scratch resistance, transportability (slipability), etc., a matting agent, a slipping agent, or the like is added to the outermost layer (or a layer adjacent to the outermost layer). Therefore, if the composition of the outermost layer is changed, these physical properties may change, and it is difficult to change the composition significantly.
Therefore, the present inventors paid attention to a non-photosensitive intermediate layer between the image forming layer and the outermost layer. In order to effectively prevent moisture and the like from entering the image forming layer from the outside, it has been found that it is important to make the layer adjacent to the image forming layer a strongly hydrophobic layer. In order to improve, a very hydrophobic binder is applied to the non-photosensitive intermediate layer adjacent to the image forming layer. Here, a highly hydrophobic binder was examined. When the binder contains 80% by mass or more of a polymer (latex) obtained by copolymerizing the monomer represented by the general formula (M), the image storability is improved. The result was very good.

  On the other hand, the hydrophobic binder has no setability and has a problem in coating properties. The set property means that the coating solution gels and loses fluidity when the temperature decreases. By utilizing this property, the fluidity can be stopped by applying a heated coating solution on the support and then cooling. Therefore, when a coating solution having setability is used, unevenness hardly occurs due to wind during drying, and the coated surface is uniform. In the present invention, in order to improve the coating surface condition and the coating work efficiency, the animal protein-derived water-soluble solution is provided in any layer farther from the support than the non-photosensitive intermediate layer A containing a highly hydrophobic binder. A layer containing a functional polymer (such as gelatin) was provided. By adopting such a layer configuration, the fluidity of the image forming layer surface is lost, and the coated surface is also uniform. In a photothermographic material, since there is no swelling due to processing with a developing solution, slight unevenness of the coated surface at the time of production appears as density unevenness or haze, which may hinder image diagnosis. In photothermographic materials, the uniformity of the coating film is one of the extremely important performances.

  Furthermore, a photothermographic material having a composition capable of rapidly processing heat development is more susceptible to influence from the external environment. As a light-sensitive material composition for rapid processing, (1) a reducing agent having high activity, (2) a development accelerator is added, (3) a specific antifogging agent is used, (4) specific It is characterized by the addition of a color toning agent. Also in such a rapid developing photothermographic material, the photothermographic material having the above layer structure is excellent in image storability.

  The present invention provides a photothermographic material excellent in image storability (raw storability) of an unexposed photosensitive material and image storability after exposure, and an image forming method thereof.

The photothermographic material of the present invention is a photothermographic material in which an image forming layer containing a photosensitive silver halide, a non-photosensitive organic acid silver salt, a reducing agent, and a binder is provided on at least one side of a support. A non-photosensitive material containing a binder adjacent to the image forming layer, wherein the outermost layer is provided on the side of the support on which the image forming layer is provided on the side farthest from the support. The intermediate layer A is provided, and the binder of the non-photosensitive intermediate layer A contains 80% by mass or more of a polymer obtained by copolymerizing a monomer represented by the following general formula (M). A non-photosensitive intermediate layer B containing a binder is provided between the layer A and the outermost layer, and at least one of the outermost layer and the non-photosensitive intermediate layer B has hydrophilicity derived from animal protein. Contains 50% by weight or more of polymer Characterized in that it comprises a binder.
Below, the layer constitution of the photothermographic material of the present invention will be explained first, and then the components of each layer will be explained.

1. Layer Structure The photothermographic material of the invention has at least one image forming layer, and has a non-photosensitive intermediate layer between the outermost layer and the image forming layer. At least two non-photosensitive intermediate layers are provided, which are a non-photosensitive intermediate layer A and a non-photosensitive intermediate layer B, respectively. The non-photosensitive intermediate layer A is provided adjacent to the image forming layer, and the non-photosensitive intermediate layer B is provided between the non-photosensitive intermediate layer A and the outermost layer. The binder of the non-photosensitive intermediate layer A contains 80% by mass or more of latex of a polymer obtained by copolymerizing the monomer represented by the general formula (M). In at least one of the outermost layer and the non-photosensitive intermediate layer B, the binder contains 50% by mass or more of a hydrophilic polymer derived from animal protein.
That is, the layers essential as the layer structure are (1) the image forming layer, (2) the non-photosensitive intermediate layer A, (3) the non-photosensitive intermediate layer B, and (4) the outermost layer from the support side. As long as the image forming layer and the non-photosensitive intermediate layer A are provided adjacent to each other, each layer may be a single layer or two or more layers, or another layer may be provided.

Usually, the role of the outermost layer is to provide transportability and scratch resistance and to prevent adhesion of the image forming layer. Therefore, in addition to the binder, additives such as a matting agent, a slipping agent, and a surfactant are often added to the outermost layer. In addition to the outermost layer, a single or multiple surface protective layer may be provided. The surface protective layer is described in JP-A No. 11-65021, paragraph numbers 0119 to 0120 and JP-A No. 2000-171936.
The intermediate layer is often provided as a boundary layer between the image forming layer and the outermost layer, and most of the layer is usually occupied by a binder. In addition, various additives can be added to the intermediate layer.

  For the non-photosensitive intermediate layer B and the outermost layer, preferred layer configurations (preferred binder types) are shown below, but are not limited thereto.

  Hereinafter, a polymer obtained by copolymerizing the monomer represented by the general formula (M) is referred to as “polymer of the general formula (M)”, and a hydrophobic polymer (a monomer represented by the general formula (M) is copolymerized). (But not limited to polymers) are referred to as “hydrophobic polymers”, hydrophilic polymers derived from animal proteins (eg, gelatin) are referred to as “hydrophilic polymers 1”, and hydrophilic polymers that are not derived from animal proteins (eg, What contains 50 mass% or more of polyvinyl alcohol (PVA)) is referred to as “hydrophilic polymer 2”.

In the present invention, a layer containing a binder containing 50% by mass or more of the hydrophilic polymer 1 is provided on the side farther from the support than the non-photosensitive intermediate layer A.
In consideration of coating performance for the outermost layer, the binder preferably contains 50% by mass or more of hydrophilic polymer 1 such as gelatin, and preferably contains a hydrophobic polymer in consideration of image storability due to stickiness and finger marks. .
In any one of the layer configurations 3, 4, and 6, the hydrophilic polymer 2 can be used in place of the outermost hydrophilic polymer 1.

  In consideration of coating performance, the non-photosensitive intermediate layer B preferably contains 50% by mass or more of the hydrophilic polymer 1 in consideration of suppressing aggregation due to contact between the gelatin-containing layer and the hydrophobic polymer-containing layer. In this case, it is preferable to form two layers with a layer containing 50% by mass or more of the hydrophilic polymer 2 such as PVA.

(I) When the outermost layer binder does not contain 50% by mass or more of the hydrophilic polymer 1 When the outermost layer binder does not contain 50% by mass or more of the hydrophilic polymer 1, in order to obtain the effects of the present invention, it is non-photosensitive. The binder of the hydrophilic intermediate layer B must contain 50% by mass or more of the hydrophilic polymer 1. In this case, the outermost binder may be a hydrophilic polymer or a hydrophobic polymer. When the outermost layer binder contains a hydrophilic polymer, the hydrophilic polymer may be either the hydrophilic polymer 1 or the hydrophilic polymer 2. In consideration of setting properties, it is preferable that the binder in the outermost layer also contains 50% by mass or more of the hydrophilic polymer 1, or a gelling agent is added to the hydrophilic polymer 2. When a hydrophobic polymer is used for the outermost layer, finger print adhesion and stickiness can be suppressed, and such a layer structure is also preferable. These polymers can be used in combination regardless of whether they are hydrophilic polymers or hydrophobic polymers.

(Ii) When the outermost layer binder contains 50% by mass or more of the hydrophilic polymer 1 When the outermost layer binder contains 50% by mass or more of the hydrophilic polymer 1, the binder of the non-photosensitive intermediate layer B is not particularly limited. However, a binder containing 50% by mass or more of the hydrophilic polymer 1 or a binder containing 50% by mass or more of the hydrophilic polymer 2 is preferable. In consideration of transportability and scratch resistance, additives such as a matting agent and a surfactant are often added to the outermost layer, and the binder content is often limited. Therefore, when a binder containing 50% by mass or more of the hydrophilic polymer 1 is used in the outermost layer, the coating performance is further improved by using a binder containing 50% by mass or more of the hydrophilic polymer 1 in the non-photosensitive intermediate layer B. Improvement is also a preferred embodiment. More preferably, two or more non-photosensitive intermediate layers B are provided, and the binder of the non-photosensitive intermediate layer B on the side close to the non-photosensitive intermediate layer A contains 50% by mass or more of the hydrophilic polymer 2, and is the outermost layer. The binder of the non-photosensitive intermediate layer B on the near side is a case where the hydrophilic polymer 1 is contained in an amount of 50% by mass or more. By providing the non-photosensitive intermediate layer B containing 50% by mass or more of the hydrophilic polymer 2, aggregation due to contact between the gelatin layer and the hydrophobic layer can be suppressed.

Usually, the photothermographic material is a non-photosensitive layer such as an undercoat layer provided between the image forming layer and the support, a back layer provided on the opposite side of the image forming layer, and farther from the support than the back layer. A back surface protective layer is further provided on the side. These layers may be each independently a single layer or a plurality of layers.
In addition, a layer acting as an optical filter can be provided, and is usually provided as an outermost layer or an intermediate layer. The antihalation layer is provided in the photothermographic material as an undercoat layer or a back layer.

  The photothermographic material of the present invention may be a single-sided type having an image forming layer only on one side of a support, or a double-sided type having image forming layers on both sides of a support. In the case of a double-sided type, the other surface is not particularly limited as long as at least one surface has the above-described layer configuration.

  The construction of a multicolor photosensitive photothermographic material may include a combination of these two layers for each color and all components in a single layer as described in US Pat. No. 4,708,928. May be included. In the case of a multi-dye multicolor photothermographic material, each image forming layer is generally between each photosensitive layer (image forming layer) as described in US Pat. No. 4,460,681. By using functional or non-functional barrier layers, they are kept distinct from each other.

2. In the following, the non-photosensitive intermediate layer A containing the polymer of the general formula (M) will be described in detail. Next, a layer containing 50% by mass or more of the hydrophilic polymer 1 that can be used for the non-photosensitive intermediate layer B and the outermost layer (hereinafter referred to as “hydrophilic polymer 1-containing layer”) and the hydrophilic polymer 2 are contained. A layer (hereinafter referred to as “hydrophilic polymer 2 containing layer”) and a layer containing a hydrophobic polymer (hereinafter referred to as “hydrophobic polymer containing layer”) will be described. These layers can be used for both the outermost layer and the non-photosensitive intermediate layer B.

(1) Non-photosensitive intermediate layer A
In the present invention, the binder of the non-photosensitive intermediate layer A contains 80% by mass or more of a polymer obtained by copolymerizing the monomer represented by the general formula (M).

  In the binder in the non-photosensitive intermediate layer A, the content of the polymer obtained by copolymerizing the monomer represented by the general formula (M) is 80% by mass or more, preferably 85% by mass or more and 100% by mass or less. More preferably, it is 90 mass% or more and 100 mass% or less. When the copolymerization ratio of the monomer represented by formula (M) is less than 80% by mass, the effect of improving the image storage stability is small.

General formula (M)
CH ₂ = CR ⁰¹ -CR ⁰² = CH ₂
In the formula, R ⁰¹ and R ⁰² are a group selected from a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a halogen atom, or a cyano group.

The preferred alkyl group for R ⁰¹ and R ^{02 is} an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 to 2 carbon atoms. As the halogen atom, a fluorine atom, a chlorine atom or a bromine atom is preferable, and a chlorine atom is more preferable.
R ⁰¹ and R ⁰² are particularly preferably both hydrogen atoms, or one is a hydrogen atom and the other is a methyl group or a chlorine atom.

  Specific examples of the monomer represented by the general formula (M) in the present invention include 1,3-butadiene, 2-ethyl-1,3-butadiene, 2-n-propyl-1,3-butadiene, 2,3. -Dimethyl-1,3-butadiene, 2-methyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1-bromo-1,3-butadiene, 2-fluoro-1,3-butadiene, 2 , 3-dichloro-1,3-butadiene and 2-cyano-1,3-butadiene.

In the present invention, the other monomer that can be copolymerized with the monomer represented by formula (M) is not particularly limited, and any monomer that can be polymerized by a normal radical polymerization or ionic polymerization method is preferably used. be able to.
The monomers that can be preferably used can be selected independently and freely in combination from the monomer groups (a) to (j) shown below.

-Monomer group (a)-(j)-
(A) Conjugated dienes: 1,3-butadiene, 1,3-pentadiene, 1-phenyl-1,3-butadiene, 1-α-naphthyl-1,3-butadiene, 1-β-naphthyl-1,3 -Butadiene, 1-bromo-1,3-butadiene, 1-chloro-1,3-butadiene, 1,1,2-trichloro-1,3-butadiene, cyclopentadiene and the like.
(B) Olefin: ethylene, propylene, vinyl chloride, vinylidene chloride, 6-hydroxy-1-hexene, 4-pentenoic acid, methyl 8-nonenoate, vinylsulfonic acid, trimethylvinylsilane, trimethoxyvinylsilane, 1,4- Divinylcyclohexane, 1,2,5-trivinylcyclohexane, etc. (c) α, β-unsaturated carboxylic acid and salts thereof: acrylic acid, methacrylic acid, itaconic acid, maleic acid, sodium acrylate, ammonium methacrylate, itaconic acid Potassium and the like.

  (D) α, β-unsaturated carboxylic acid esters: alkyl acrylates (for example, methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate) A substituted alkyl acrylate (for example, 2-chloroethyl acrylate, benzyl acrylate, 2-cyanoethyl acrylate, etc.), an alkyl methacrylate (for example, methyl methacrylate). Acrylate, butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, etc.), substituted alkyl methacrylate (for example, 2-hydroxyethyl methacrylate, glycidyl methacrylate). Glycerin monomethacrylate, 2-acetoxyethyl methacrylate, tetrahydrofurfuryl methacrylate Acrylate, 2-methoxyethyl methacrylate, polypropylene glycol monomethacrylate (polyoxypropylene added mole number = 2 to 100), 3-N, N-dimethylaminopropyl methacrylate Chloro-3-N, N, N-trimethylammoniopropyl methacrylate, 2-carboxyethyl methacrylate, 3-sulfopropyl methacrylate, 4-oxysulfobutyl methacrylate, 3- Trimethoxysilylpropyl methacrylate, aryl methacrylate, 2-isocyanatoethyl methacrylate, etc.) and unsaturated dicarboxylic acid derivatives (eg, monobutyl maleate, dimethyl maleate, monomethyl itaconate, itaconic acid) Dibutyl, etc.), polyfunctional esters (for example, ethylene glycol diacrylate) Ethylene glycol dimethacrylate, 1,4-cyclohexane diacrylate, pentaerythritol tetramethacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylol Ethane triacrylate, dipentaerythritol pentamethacrylate, pentaerythritol hexaacrylate, 1,2,4-cyclohexanetetramethacrylate, etc.).

(E) Amides of β-unsaturated carboxylic acid: for example, acrylamide, methacrylamide, N-methylacrylamide, N, N-dimethylacrylamide, N-methyl-N-hydroxyethylmethacrylamide, N-tertbutylacrylamide, N- tert-octylmethacrylamide, N-cyclohexylacrylamide, N-phenylacrylamide, N- (2-acetoacetoxyethyl) acrylamide, N-acryloylmorpholine, diacetoneacrylamide, itaconic acid diamide, N-methylmaleimide, 2-acrylamido-methyl Propanesulfonic acid, methylenebisacrylamide, dimethacryloylpiperazine, etc.
(F) Unsaturated nitriles: acrylonitrile, methacrylonitrile and the like.
(G) Styrene and its derivatives: styrene, vinyl toluene, p-tertbutyl styrene, vinyl benzoic acid, methyl vinyl benzoate, α-methyl styrene, p-chloromethyl styrene, vinyl naphthalene, p-hydroxymethyl styrene, p- Styrene sulfonic acid sodium salt, p-styrene sulfinic acid potassium salt, p-aminomethylstyrene, 1,4-divinylbenzene and the like.
(H) Vinyl ethers: methyl vinyl ether, butyl vinyl ether, methoxyethyl vinyl ether, and the like.
(I) Vinyl esters: vinyl acetate, vinyl propionate, vinyl benzoate, vinyl salicylate, vinyl chloroacetate, and the like.
(J) Other polymerizable monomers: N-vinylimidazole, 4-vinylpyridine, N-vinylpyrrolidone, 2-vinyloxazoline, 2-isopropenyloxazoline, divinylsulfone, and the like.

Preference is given to copolymerization with styrene, acrylic acid and / or acrylic esters. Furthermore, a copolymer having styrene and acrylic acid as monomer units is preferred because the resulting hydrophobic polymer can be used as an aqueous dispersion having good dispersion stability.
The copolymerization ratio of the monomer represented by the general formula (M) and the other monomer is not particularly limited, but preferably the monomer represented by the general formula (M) is 10% by mass or more and 70% by mass or less. The copolymerization is preferably 15% by mass to 65% by mass, more preferably 20% by mass to 60% by mass.

  The Tg of the polymer obtained by copolymerizing the monomer represented by the general formula (M) is preferably in the range of −30 ° C. or more and 70 ° C. or less. More preferably, it is -10 degreeC or more and 35 degrees C or less, Most preferably, it is 0 degreeC or more and 35 degrees C or less. When Tg is lower than −30 ° C., the film formability is excellent, but the film has weak heat resistance strength. When it is higher than 70 ° C., the polymer has excellent heat resistance strength, but the film formability is poor. Since it becomes a sufficient film | membrane, it is not preferable. However, in order to obtain such a Tg, it is also possible to prepare using two or more kinds of polymers. That is, even if the polymer has a Tg outside the above range, the mass average Tg is preferably within the above range.

  The polymer obtained by copolymerizing the monomer represented by the general formula (M) preferably has an I / O value of 0.025 or more and 0.3 or less. More preferably, it is 0.05 or more and 0.15 or less. The I / O value is a value obtained by dividing an inorganic group based on an organic conceptual diagram by an organic group. When the I / O value is lower than 0.025, the affinity for the aqueous solvent is poor, and it becomes difficult to apply with an aqueous coating solution. When the I / O value is higher than 0.3, the finished film is hydrophilic. It is not preferable because the film becomes a thick film, affects the photographic properties with respect to humidity, and remarkably deteriorates photographic performance. The I / O value can be determined by the method described in “Organic Conceptual Diagram-Basics and Applications” (1984 Yoshio Koda, Sankyo Publishing).

  Here, an organic conceptual diagram is an orthogonal coordinate system in which the properties of a compound are divided into an organic group representing a covalent bond and an inorganic group representing an ionic bond, and all organic compounds are named organic and inorganic axes. The inorganic value based on this is determined based on the hydroxyl group based on the inorganicity, that is, the influence of various substituents on the boiling point. If the distance between the boiling point curve of the straight-chain paraffin and the straight-line paraffin is about 100 ° C., the influence of one hydroxyl group is 100. On the other hand, the organic value is based on the number of carbon atoms that represent the methylene group in units of the number of methylene groups in the molecule. The average value of the boiling point increase due to addition of one carbon in the vicinity of 5 to 10 carbon atoms of the linear compound is 20 ° C., and this is a value determined as 20 on the basis of this. The inorganic value and the organic value are determined so as to correspond one-to-one on the graph. The I / O value is calculated from these values.

In the present invention, the polymer obtained by copolymerizing the monomer represented by the general formula (M) is preferably contained in the coating solution as an aqueous dispersion. The aqueous dispersion may be either latex in which fine particles of a hydrophobic polymer insoluble in an aqueous solvent are dispersed, or in which polymer molecules are dispersed in a molecular state or forming micelles. Is more preferable.
The average particle size of the dispersed particles is 1 nm or more and 50000 nm or less, preferably 5 nm or more and 1000 nm or less, more preferably 10 nm or more and 500 nm or less, and further preferably 50 nm or more and 200 nm or less. The particle size distribution of the dispersed particles is not particularly limited, and may have a wide particle size distribution or a monodispersed particle size distribution. Mixing two or more types having a monodispersed particle size distribution is also a preferable method for controlling the physical properties of the coating solution.

1) Preferred Latex The polymer latex used in the present invention is particularly preferably a styrene-butadiene copolymer or styrene-isoprene copolymer latex. In the styrene-butadiene copolymer or styrene-isoprene copolymer, the mass ratio of the styrene monomer unit to the butadiene or isoprene monomer unit is preferably 40:60 to 95: 5.
Further, the polymer latex in the present invention preferably contains acrylic acid or methacrylic acid in an amount of 1% by mass to 6% by mass, more preferably 2% by mass to 5% by mass with respect to the sum of styrene and butadiene. . The polymer latex in the present invention preferably contains acrylic acid. The preferred molecular weight range is the same as described above.

2) Specific Examples of Latex Specific examples of preferable polymer latex include the following. Below, it represents using a raw material monomer, the numerical value in a parenthesis is the mass%, and molecular weight is a number average molecular weight. When a polyfunctional monomer was used, the concept of molecular weight was not applicable because a crosslinked structure was formed, so it was described as crosslinkability, and the description of molecular weight was omitted. Tg represents the glass transition temperature.

-P-1; Latex of -St (62) -Bu (35) -MAA (3)-(crosslinkability, Tg 5 ° C)
-P-2; -St (68) -Bu (29) -AA (3)-latex (crosslinkable, Tg 17 ° C.)
-P-3; -St (71) -Bu (26) -AA (3)-latex (crosslinkability, Tg 24 ° C)
-P-4; Latex of -St (70) -Bu (27) -IA (3)-(crosslinkability, Tg 23 ° C)
* P-5; Latex of -St (75) -Bu (24) -AA (1)-(crosslinkability, Tg 29 ° C.)
-P-6; Latex of -St (60) -Bu (35) -DVB (3) -MAA (2)-(crosslinkability, Tg 6 ° C.)
-P-7; Latex of -St (70) -Bu (25) -DVB (2) -AA (3)-(crosslinkability, Tg 26 ° C.)
・ P-8; Latex of -St (70.5) -Bu (26.5) -AA (3)-(crosslinkability, Tg23 ° C)
・ P-9; Latex of -St (69.5) -Bu (27.5) -AA (3)-(crosslinkability, Tg 20.5 ° C)
-P-10; Latex of -St (61.3) -isoprene (35.5) -AA (3)-(crosslinkability, Tg 17 ° C)
-Latex of P-11; -St (67) -isoprene (28) -Bu (2) -AA (3)-(crosslinkability, Tg 27 ° C.)

  The abbreviations for the above structures represent the following monomers. MAA; methacrylic acid, St; styrene, Bu; butadiene, AA; acrylic acid, DVB; divinylbenzene, IA;

As latexes of styrene-butadiene copolymers that are preferably used in the present invention, P-1 to P-9, LACSTAR-3307B and 7132C (commercially available from Dainippon Ink & Chemicals, Inc.), which are commercially available products, are used. Nipol Lx416 (manufactured by Nippon Zeon Co., Ltd.) and the like.
Examples of the latex of the styrene-isoprene copolymer include the aforementioned P-10 and P-11.

  These polymer latexes may be used alone or in combination of two or more as required. Further, other polymers may be used in combination.

The polymer that can be used in combination may be a hydrophobic polymer or a hydrophilic polymer.
Examples of the hydrophilic polymer that can be used in combination include gelatin, polyvinyl alcohol, methylcellulose, hydroxypropylcellulose, carboxymethylcellulose, sodium polyacrylate, and the like. The amount of these hydrophilic polymers added is preferably 30% by mass or less, more preferably 10% by mass or less, based on the total binder of the non-photosensitive intermediate layer.
Examples of the hydrophobic polymer that can be used in combination include polyacrylate, polyurethane, polymethacrylate, or a copolymer containing these (latex) that can be used in the hydrophobic polymer layer described below. The amount of these hydrophobic polymers added is preferably 30% by mass or less, more preferably 10% by mass or less, based on the total binder of the non-photosensitive intermediate layer.

3) Film-forming aid that can be used in combination In order to control the minimum film-forming temperature of the aqueous dispersion of hydrophobic polymer, a film-forming aid may be added. The film-forming aid is also called a temporary plasticizer, and is an organic compound (usually an organic solvent) that lowers the minimum film-forming temperature of the polymer latex. (1970)) Preferred film-forming aids are the following compounds, but the compounds that can be used in the present invention are not limited to the following specific examples.
Z-1: benzyl alcohol Z-2: 2,2,2,4-trimethylpentanediol-1,3-monoisobutyrate Z-3: 2-dimethylaminoethanol Z-4: diethylene glycol

4) Addition amount The content of the polymer obtained by copolymerizing the monomer represented by the general formula (M) is preferably 5% by mass or more and 50% by mass or less with respect to the entire coating solution for the non-photosensitive intermediate layer A. More preferably, it is 10 mass% or more and 40 mass% or less.

5) Coating amount The coating amount of the polymer obtained by copolymerizing the monomer represented by the general formula (M) of the non-photosensitive intermediate layer A is preferably 0.1 g / m ² or more and 10 g / m ² or less, More preferably, it is 0.3 g / m ² or more and 7 g / m ² or less, and most preferably 0.5 g / m ² or more and 5 g / m ² or less.

6) Crosslinking agent In the present invention, it is preferable to include a crosslinking agent in any layer of the image forming layer surface. More preferably, it is a case where it is added to the hydrophilic polymer 1-containing layer or the hydrophilic polymer 2-containing layer such as the non-photosensitive intermediate layer B. By adding a crosslinking agent, the hydrophobicity and water resistance of the non-photosensitive intermediate layer are increased, and an excellent photothermographic material is obtained.

  As a crosslinking agent, what is necessary is just to contain two or more groups which react with an amino group or a carboxyl group in a molecule | numerator, and it does not specifically limit about the kind of crosslinking agent. Examples of cross-linking agents include T.W. H. "THE THEORY OF THE PHOTOGRAPHIC PROCESS FOURTH EDITION" by James (published by Macmillan Publishing Co., Inc., 1977), pages 77-87, and inorganic compound cross-linking agents (for example, chromium alum) Any of the compound crosslinking agents is preferred, but organic compound crosslinking agents are more preferred.

The crosslinking agent for the hydrophobic polymer-containing layer such as the non-photosensitive intermediate layer A of the present invention may contain a plurality of groups that react with carboxyl groups in the molecule, and the type of the crosslinking agent is not particularly limited. .
Preferred examples of the organic compound crosslinking agent include carboxylic acid derivatives, carbamic acid derivatives, sulfonic acid ester compounds, sulfonyl compounds, epoxy compounds, aziridine compounds, isocyanate compounds, carbodiimide compounds, and oxazoline compounds. More preferred are epoxy compounds, isocyanate compounds, carbodiimide compounds and oxazoline compounds. These crosslinking agents may be used alone or in combination of two or more.

  Specific examples include the following compounds, but the present invention is not limited to the following examples.

(Carbodiimide compound)
A water-soluble or water-dispersible carbodiimide compound is preferred, and examples thereof include polycarbodiimides derived from isophorone diisocyanate described in JP-A-59-187029 and JP-B-5-27450, and described in JP-A-7-330849. Examples thereof include carbodiimide compounds derived from tetramethylxylylene diisocyanate, other branched carbodiimide compounds described in JP-A-10-30024, and carbodiimide compounds derived from dicyclohexylmethane diisocyanate described in JP-A 2000-7642.

(Oxazoline compound)
A water-soluble or water-dispersible oxazoline compound is preferable, and examples thereof include an oxazoline compound described in JP-A No. 2001-215653. .

(Isocyanate compound)
Since it is a compound that can react with water, a water-dispersible isocyanate compound is preferable from the viewpoint of pot life, and a compound having self-emulsifying properties is particularly preferable. Examples include JP-A-7-304841, JP-A-8-277315, JP-A-10-45866, JP-A-9-71720, JP-A-9-328654, JP-A-9-104814. And water dispersible isocyanate compounds described in JP-A Nos. 2000-194045, 2000-194237, and 2003-64149.

(Epoxy compound)
Water-soluble or water-dispersible epoxy compounds are preferred, and examples thereof include water-dispersible epoxy compounds described in JP-A-6-329877 and JP-A-7-309954.

  Although the more specific example of the crosslinking agent which can be used for this invention is shown below, this invention is not limited to the following examples.

(Epoxy compound)
Product name: Dick Fine EM-60 (Dainippon Ink Chemical Co., Ltd.)

(Isocyanate compound)
Product name: DURANATE WB40-100 (Asahi Kasei Corporation)
Duranate WB40-80D (Asahi Kasei Corporation)
Duranate WT20-100 (Asahi Kasei Corporation)
Duranate WT30-100 (Asahi Kasei Corporation)
CR-60N (Dainippon Ink Chemical Co., Ltd.)

(Carbodiimide compound)
Product name: Carbodilite V-02 (Nisshinbo Co., Ltd.)
Carbodilite V-02-L2 (Nisshinbo Co., Ltd.)
Carbodilite V-04 (Nisshinbo Co., Ltd.)
Carbodilite V-06 (Nisshinbo Co., Ltd.)
Carbodilite E-01 (Nisshinbo Co., Ltd.)
Carbodilite E-02 (Nisshinbo Co., Ltd.)

(Oxazoline compound)
Product name: Epocross K-1010E (Nippon Shokubai Co., Ltd.)
Epocross K-1020E (Nippon Shokubai Co., Ltd.)
Epocross K-1030E (Nippon Shokubai Co., Ltd.)
Epocross K-2010E (Nippon Shokubai Co., Ltd.)
Epocross K-2020E (Nippon Shokubai Co., Ltd.)
Epocross K-2030E (Nippon Shokubai Co., Ltd.)
Epocross WS-500 (Nippon Shokubai Co., Ltd.)
Epocross WS-700 (Nippon Shokubai Co., Ltd.)

  The crosslinking agent used in the present invention may be added in a state of being premixed in the binder solution, may be added at the end of the coating liquid preparation process, or may be added immediately before coating.

  As a usage-amount of the crosslinking agent used for this invention, it is preferable that it is 0.5-200 mass parts with respect to 100 mass parts of binders of the constituent layer contained, and it is more preferable that it is 2-100 mass parts, Furthermore, it is more preferable that it is 3-50 mass parts.

7) Thickener It is preferable to add a thickener to the coating liquid for forming the non-photosensitive intermediate layer A. It is preferable to add a thickener since a hydrophobic layer having a uniform thickness can be formed. As the thickener, for example, an alkali metal salt of polyvinyl alcohol, hydroxyethyl cellulose, or carboxymethyl cellulose is used, but a thixotropic one is preferable in consideration of ease of handling. Therefore, hydroxyethyl cellulose, sodium hydroxymethylcarboxylate, Carboxymethyl-hydroxyethylcellulose is used.
The viscosity of the non-photosensitive intermediate layer A coating solution to which a thickener is added is preferably 1 mPa · s or more and 200 mPa · s or less, preferably 10 mPa · s or more and 100 mPa · s or less, at 40 ° C. More preferably, it is 15 mPa · s or more and 60 mPa · s or less.

  In addition to the binder, various additives can be added to the non-photosensitive intermediate layer A. For example, surfactants, pH adjusters, preservatives, antifungal agents and the like can be mentioned as additives.

(2) Hydrophilic polymer 1 containing layer In this invention, a hydrophilic polymer 1 containing layer means the layer which contains the hydrophilic polymer 1 50 mass% or more. Whether the hydrophilic polymer 1-containing layer is the outermost layer or the non-photosensitive intermediate layer B, the preferred content of the hydrophilic polymer 1 is 50% by mass or more and 100% by mass or less, more preferably 60% by mass. It is 100 mass% or less. When the content of the hydrophilic polymer not derived from animal protein is less than 50% by mass, the setting property during coating and drying is impaired, and unevenness is likely to occur in the finished surface, which is not preferable.

In the present invention, the hydrophilic polymer 1 (hydrophilic polymer derived from animal protein) refers to a natural or chemically modified water-soluble polymer such as glue, casein, gelatin, and egg white.
Gelatin is preferred, and acid-treated gelatin and alkali-treated gelatin (such as lime treatment) are available depending on the synthesis method, and both can be preferably used. It is preferable to use gelatin having a molecular weight of 10,000 to 1,000,000. In addition, modified gelatin modified by utilizing the amino group or carboxyl group of gelatin can be used (for example, phthalated gelatin). As gelatin, inert gelatin (for example, Nitta gelatin 750), phthalated gelatin (for example, Nitta gelatin 801), or the like can be used.
The gelatin aqueous solution becomes sol when heated to a temperature of 30 ° C. or higher, and gels and loses fluidity when lowered to a temperature lower than 30 ° C. Since such a sol-gel change occurs reversibly with temperature, the gelatin aqueous solution which is a coating solution has a set property of losing fluidity when cooled to a temperature lower than 30 ° C.

The hydrophilic polymer 1 can be used in combination with the following hydrophilic polymer 2 (hydrophilic polymer not derived from animal protein) and / or hydrophobic polymer. When the hydrophilic polymer 1-containing layer is the outermost layer, it is preferable to use a hydrophobic polymer in combination as the binder. In this case, the preferred combination ratio is 50:50 to 99: 1, more preferably 50:50 to 80:20 for the hydrophilic polymer 1: hydrophobic polymer.
The content of the hydrophilic polymer 1 in the coating solution is 1% by mass or more and 20% by mass or less with respect to the entire coating solution, whether it is the outermost layer or the non-photosensitive intermediate layer B, preferably It is 2 mass% or more and 12 mass% or less.

It is preferable to add a crosslinking agent to the hydrophilic polymer 1-containing layer. Preferred crosslinking agents are the same as those described in the description of the non-photosensitive intermediate layer A.
Furthermore, a surfactant, pH adjuster, preservative, antifungal agent, dye, pigment, color tone adjuster, and the like can be added to the hydrophilic polymer 1-containing layer.

(3) Hydrophilic polymer 2 containing layer In this invention, a hydrophilic polymer 2 containing layer means the layer which contains the hydrophilic polymer 2 50 mass% or more. Whether the hydrophilic polymer 2 containing layer is the outermost layer or the non-photosensitive intermediate layer B, the preferred content of the hydrophilic polymer 2 is 50% by mass or more and 100% by mass in the total binder of the hydrophilic polymer 2 containing layer. It is below, More preferably, they are 60 mass% or more and 100 mass% or less. When the hydrophilic polymer 2 containing layer is provided between the gelatin containing layer and the non-photosensitive intermediate layer A, if the content of the hydrophilic polymer not derived from animal protein is less than 50% by mass, the effect of preventing aggregation is small. Become.

The hydrophilic polymer not derived from animal protein in the present invention is a natural polymer (polysaccharide, microbial, animal) other than animal protein such as gelatin, semi-synthetic polymer (cellulose, starch, alginic acid). ) And synthetic polymers (vinyl-based, etc.), which are synthetic polymers such as polyvinyl alcohol described below, and natural or semi-synthetic polymers made from plant-derived cellulose or the like. Polyvinyl alcohols and acrylic acid-vinyl alcohol copolymer polymers are preferable.
A hydrophilic polymer not derived from animal protein does not have setability, but when used together with a gelling agent, it has setability and good coating performance.

1) Polyvinyl alcohols Polyvinyl alcohols are preferred as hydrophilic polymers not derived from animal proteins in the present invention.
As polyvinyl alcohol (PVA) preferably used in the present invention, there are various saponification degrees, polymerization degrees, neutralization degrees, modified substances, and copolymers with various monomers as listed below.

  As a completely saponified product, PVA-105 [polyvinyl alcohol (PVA) content 94.0% by mass or more, saponification degree 98.5 ± 0.5 mol%, sodium acetate content 1.5% by mass or less, volatile content 5 0.0 mass% or less, viscosity (4 mass%, 20 ° C.) 5.6 ± 0.4 CPS], PVA-110 [PVA content 94.0 mass%, saponification degree 98.5 ± 0.5 mol%, acetic acid Sodium content 1.5% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 11.0 ± 0.8 CPS], PVA-117 [PVA content 94.0% by mass, saponification degree 98.5 ± 0.5 mol%, sodium acetate content 1.0 mass%, volatile matter 5.0 mass%, viscosity (4 mass%, 20 ° C.) 28.0 ± 3.0 CPS], PVA-117H [ PVA content 93.5% by mass, saponification degree 99.6 ± 0.3 mol% Sodium acetate content 1.85% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 29.0 ± 3.0 CPS], PVA-120 [PVA content 94.0% by mass, saponification Degree 98.5 ± 0.5 mol%, sodium acetate content 1.0 mass%, volatile matter 5.0 mass%, viscosity (4 mass%, 20 ° C.) 39.5 ± 4.5 CPS], PVA-124 [PVA content 94.0% by mass, saponification degree 98.5 ± 0.5 mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 60 0.0 ± 6.0 CPS], PVA-124H [PVA content 93.5% by mass, saponification degree 99.6 ± 0.3 mol%, sodium acetate content 1.85% by mass, volatile matter 5.0% by mass , Viscosity (4 mass%, 20 ° C.) 61.0 ± 6.0 CPS], PVA-CS [PVA Proportion 94.0% by mass, saponification degree 97.5 ± 0.5 mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 27.5 ± 3.0 CPS], PVA-CST [PVA content 94.0% by mass, saponification degree 96.0 ± 0.5 mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4 mass%, 20 ° C.) 27.0 ± 3.0 CPS], PVA-HC [PVA content 90.0 mass%, saponification degree 99.85 mol% or more, sodium acetate content 2.5 mass%, volatilization 8.5% by mass, viscosity (4% by mass, 20 ° C.) 25.0 ± 3.5 CPS] (all are trade names manufactured by Kuraray Co., Ltd.) and the like.

  As a partially saponified product, PVA-203 [PVA content 94.0% by mass, saponification degree 88.0 ± 1.5 mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4 mass%, 20 ° C.) 3.4 ± 0.2 CPS], PVA-204 [PVA content 94.0 mass%, saponification degree 88.0 ± 1.5 mol%, sodium acetate content 1.0 mass %, Volatile matter 5.0 mass%, viscosity (4 mass%, 20 ° C.) 3.9 ± 0.3 CPS], PVA-205 [PVA content 94.0 mass%, saponification degree 88.0 ± 1.5 Mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 5.0 ± 0.4 CPS], PVA-210 [PVA content 94.0% by mass %, Saponification degree 88.0 ± 1.0 mol%, sodium acetate content 1.0% by mass, volatilization 5.0 mass%, viscosity (4 mass%, 20 ° C.) 9.0 ± 1.0 CPS], PVA-217 [PVA content 94.0 mass%, saponification degree 88.0 ± 1.0 mol%, acetic acid Sodium content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 22.5 ± 2.0 CPS], PVA-220 [PVA content 94.0% by mass, saponification degree 88.0 ± 1.0 mol%, sodium acetate content 1.0 mass%, volatile matter 5.0 mass%, viscosity (4 mass%, 20 ° C.) 30.0 ± 3.0 CPS], PVA-224 [ PVA content 94.0% by mass, saponification degree 88.0 ± 1.5 mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 44. 0 ± 4.0 CPS], PVA-228 [PVA content 94.0% by mass, saponification degree 88.0 ± 1.5 %, Sodium acetate content 1.0 mass%, volatile matter 5.0 mass%, viscosity (4 mass%, 20 ° C.) 65.0 ± 5.0 CPS], PVA-235 [PVA content 94.0 mass %, Saponification degree 88.0 ± 1.5 mol%, sodium acetate content 1.0 mass%, volatile matter 5.0 mass%, viscosity (4 mass%, 20 ° C.) 95.0 ± 15.0 CPS], PVA-217EE [PVA content 94.0% by mass, saponification degree 88.0 ± 1.0 mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20% ° C) 23.0 ± 3.0 CPS], PVA-217E [PVA content 94.0 mass%, saponification degree 88.0 ± 1.0 mol%, sodium acetate content 1.0 mass%, volatile content 5. 0% by mass, viscosity (4% by mass, 20 ° C.) 23.0 ± 3.0 CPS], PVA-22 E [PVA content 94.0% by mass, saponification degree 88.0 ± 1.0 mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 31.0 ± 4.0 CPS], PVA-224E [PVA content 94.0 mass%, saponification degree 88.0 ± 1.0 mol%, sodium acetate content 1.0 mass%, volatile content 5.0 mass %, Viscosity (4 mass%, 20 ° C.) 45.0 ± 5.0 CPS], PVA-403 [PVA content 94.0 mass%, saponification degree 80.0 ± 1.5 mol%, sodium acetate content 1 0.0 mass%, volatile matter 5.0 mass%, viscosity (4 mass%, 20 ° C.) 3.1 ± 0.3 CPS], PVA-405 [PVA content 94.0 mass%, saponification degree 81.5 ± 1.5 mol%, sodium acetate content 1.0 mass%, volatile content 5.0 mass%, viscosity (4 mass %, 20 ° C.) 4.8 ± 0.4 CPS], PVA-420 [PVA content 94.0% by mass, saponification degree 79.5 ± 1.5 mol%, sodium acetate content 1.0% by mass, volatilization Min 5.0 mass%], PVA-613 [PVA content 94.0 mass%, saponification degree 93.5 ± 1.0 mol%, sodium acetate content 1.0 mass%, volatile content 5.0 mass% , Viscosity (4 mass%, 20 ° C.) 16.5 ± 2.0 CPS], L-8 [PVA content 96.0 mass%, saponification degree 71.0 ± 1.5 mol%, sodium acetate content 1. 0 mass% (ash content), volatile content 3.0 mass%, viscosity (4 mass%, 20 ° C.) 5.4 ± 0.4 CPS] (all are trade names manufactured by Kuraray Co., Ltd.), etc. Can do.

  In addition, said measured value was calculated | required according to JISK-6726-1977.

  The modified polyvinyl alcohol can be selected from cationic modification, anion modification, modification with -SH compound, modification with alkylthio compound, and modification with silanol. In addition, modified polyvinyl alcohol described in “Poval” Koichi Nagano et al.

  As such modified polyvinyl alcohol (modified PVA), C polymer as C-118, C-318, C-318-2A, C-506 (all are trade names manufactured by Kuraray Co., Ltd.), HL polymer HL-12E, HL-1203 (all are trade names made by Kuraray Co., Ltd.), HM polymer is HM-03, HM-N-03 (all are trade names made by Kuraray Co., Ltd.), KL-118, KL-318, KL-506, KM-118T, KM-618 (all are trade names manufactured by Kuraray Co., Ltd.) as the K polymer, and M-115 (manufactured by Kuraray Co., Ltd.) as the M polymer. (Trade name), MP-102, MP-202, MP-203 (all are trade names made by Kuraray Co., Ltd.) as MP polymers, and MPK-1, MPK- as MPK polymers. , MPK-3, MPK-4, MPK-5, MPK-6 (all are trade names manufactured by Kuraray Co., Ltd.), R-1130, R-2105, R-2130 (all are all as R polymers) Kuraray Co., Ltd. product name), V polymer V-2250 (Kuraray Co., Ltd. product name) and the like.

  Polyvinyl alcohol can be adjusted in viscosity or stabilized by a small amount of solvent or inorganic salt added to the aqueous solution. For details, refer to the above-mentioned document “Poval” Koichi Nagano et al. Publications described on pages 144 to 154 can be used. As a typical example, it is possible to improve the coating surface quality by containing boric acid, which is preferable. It is preferable that the addition amount of boric acid is 0.01 mass% or more and 40 mass% or less with respect to polyvinyl alcohol.

Polyvinyl alcohol is described in the above-mentioned document “Poval” that the crystallinity is improved by heat treatment and the water resistance is improved. However, it is heated at the time of coating and drying, or is additionally heated after drying. Since water resistance improves by processing, it is particularly preferable for the present invention among water-soluble polymers.
In order to further improve the water resistance, it is preferable to add a water-proofing agent as described in pages 256 to 261 of the same document. For example, aldehydes, methylol compounds (N-methylol urea, N-methylol melamine, etc.), activated vinyl compounds (divinyl sulfone and derivatives thereof), bis (β-hydroxyethyl sulfone), epoxy compounds (epichlorohydrin, Derivatives thereof), polycarboxylic acids (dicarboxylic acids, polycarboxylic acids such as polyacrylic acid, methyl vinyl ether-maleic acid copolymers, isobutylene-maleic anhydride copolymers), diisocyanates, inorganic crosslinking agents (Cu , B, Al, Ti, Zr, Sn, V, Cr, etc.).
As the water-resistant agent preferable in the present invention, inorganic crosslinking agents can be mentioned, among which boric acid and derivatives thereof are preferable, and boric acid is particularly preferable. Hereinafter, specific examples of boric acid derivatives will be given.

  The addition amount of these water-resistant agents is preferably adjusted within a range of 0.01% by mass to 40% by mass with respect to polyvinyl alcohol.

2) Hydrophilic polymer 2 other than PVA
Examples of the hydrophilic polymer 2 in the present invention include the followings in addition to the polyvinyl alcohol.

Specific examples include plant-based polysaccharides such as gum arabic, κ-carrageenan, ι-carrageenan, λ-carrageenan, guar gum (such as Supercol from Squalon), locust bean gum, pectin, tragacanth, and corn starch (National Starch & Chemical Co. Purity-21 etc.) and phosphorylated starch (National Star & Chemical Co. National 78-1898 etc.).
Examples of the microbial polysaccharide include xanthan gum (Kelco's Keltrol T, etc.) and dextrin (National Starch & Chemical Co., Nadex 360, etc.). Examples of the animal polysaccharide include sodium chondroitin sulfate (Croda CS, etc.).
Alternatively, as the cellulose-based polymer, ethyl cellulose (such as Cellfas WLD manufactured by ICI), carboxymethylcellulose (such as CMC manufactured by Daicel), hydroxyethylcellulose (such as HEC manufactured by Daicel), hydroxypropylcellulose (such as Klucel manufactured by Aqualon), methylcellulose, etc. (Viscontran manufactured by Henkel, etc.), nitrocellulose (Isopropyl Wet manufactured by Hercules, etc.), cationized cellulose (Crodacel QM manufactured by Croda, etc.) and the like.
Examples of the alginic acid system include sodium alginate (Keltone from Kelco), propylene glycol alginate, and other classifications such as cationized guar gum (such as Hi-care 1000 from Alcolac) and sodium hyaluronate (such as Hyalure from Lifecare Biomedia). .
In addition, agar, farsellan, guar gum, karaya gum, larch gum, guar seed gum, sylum seed gum, kins seed gum, tamarind gum, gellan gum, tara gum and the like can be mentioned. Among these, those having high water solubility are preferable, and those that become an aqueous solution that can be sol-gel modified within 24 hours due to a temperature change in a temperature range of 5 ° C. to 95 ° C. are preferably used.

  Synthetic polymers include acrylic poly-sodium acrylate, polyacrylic acid copolymer, polyacrylamide, polyacrylamide copolymer, etc., vinyl-based polyvinyl pyrrolidone, polyvinyl pyrrolidone copolymer, etc. Glycol, polypropylene glycol, polyvinyl ether, polyethyleneimine, polystyrene sulfonic acid or copolymer thereof, polyvinyl sulfonic acid or copolymer thereof, polyacrylic acid or copolymer thereof, acrylic acid or copolymer thereof, and maleic acid Copolymer, maleic acid monoester copolymer, acryloylmethylpropanesulfonic acid or a copolymer thereof, and the like.

Further, the superabsorbent polymer described in US Pat. No. 4,960,681, JP-A-62-245260, etc., that is, —COOM or —SO ₃ M (M is a hydrogen atom or an alkali metal). Homopolymers of vinyl monomers having a copolymer or copolymers of these vinyl monomers or other vinyl monomers (for example, sodium methacrylate, ammonium methacrylate, Sumika Gel L-5H manufactured by Sumitomo Chemical Co., Ltd.) can also be used. .

  Among these, the water-soluble polymer preferably used is Sumikagel L-5H manufactured by Sumitomo Chemical Co., Ltd.

3) Coating amount of hydrophilic polymer 2 The coating amount of hydrophilic polymer 2 (per 1 m ^{2 of} support) is preferably 0.1 g / m ² or more and 10 g / m ² or less, and 0.3 g / m ² or more and 3 g. / M ² or less is more preferable.
The concentration in the coating solution is preferably adjusted so that the viscosity becomes a value suitable for simultaneous multilayer coating when added, but is not particularly limited. In general, the concentration in the liquid is 5% by mass or more and 20% by mass or less, more preferably 7% by mass or more and 15% by mass or less, and particularly preferably 8% by mass or more and 13% by mass or less.

4) Polymer that can be used in combination With the hydrophilic polymer 2 in the present invention, a polymer that can be dispersed in an aqueous solvent may be used in combination.
Suitable water-dispersible polymers include synthetic resins, polymers and copolymers, and other film-forming media such as cellulose acetates, cellulose acetate butyrate, poly (methyl methacrylic acid), poly (vinyl chloride) , Poly (methacrylic acid) s, styrene-maleic anhydride copolymers, styrene-acrylonitrile copolymers, styrene-butadiene copolymers, poly (vinyl acetal) s (eg, poly (vinyl formal) and Poly (vinyl butyral)), poly (ester), poly (urethane), phenoxy resin, poly (vinylidene chloride), poly (epoxide), poly (carbonate), poly (vinyl acetate), poly ( Olefins), cellulose esters, poly (amides) Kill.
Preferred latexes that can be used in combination are latexes that can be used in the non-photosensitive intermediate layer A of the present invention, polyacrylates, polyurethanes, polymethacrylates, or latexes of copolymers containing these.

Specific examples of preferable latexes that can be used in combination with the hydrophilic polymer 2 will be given.
LP-1; -MMA (70) -EA (27) -MAA (3) -latex (molecular weight 37000, Tg 61 ° C.)
LP-2; -MMA (70) -2EHA (20)-St (5)-AA (5)-latex (molecular weight 40000, Tg 59 ° C)
LP-3; -VC (50) -MMA (20) -EA (20) -AN (5) -AA (5)-latex (molecular weight 80000)
LP-4; -VDC (85) -MMA (5) -EA (5) -MAA (5)-latex (molecular weight 67000)
LP-5; Latex of -Et (90) -MAA (10)-(molecular weight 12000)
LP-6; -MMA (42)-BA (56)-AA (2)-latex (molecular weight 540000, Tg-4 ° C)
LP-7; latex of MMA (63) -EA (35) -AA (2)-(molecular weight 33000, Tg 47 ° C.)
LP-8; Latex of -St (70.5) -Bu (26.5) -AA (3)-(crosslinkability, Tg 23 ° C) LP-9; -St (69.5) -Bu (27 .5) Latex of -AA (3)-(crosslinkability, Tg 20.5 ° C.)
-Latex of LP-10; -St (70) -2EHA (27) -AA (3)-(molecular weight 130,000, Tg 43 ° C)

  The abbreviations for the above structures represent the following monomers. MMA; Methyl methacrylate, EA; Ethyl acrylate, MAA; Methacrylic acid, 2EHA; 2-Ethylhexyl acrylate, St; Styrene, Bu; Butadiene, AA; Acrylic acid, DVB; Divinylbenzene, VC; Vinyl chloride, AN; Acrylonitrile, VDC Vinylidene chloride, Et; ethylene, IA; itaconic acid.

  In addition, various commercially available aqueous resins can be used as examples of preferable water-soluble polymers or polymer latexes that can be used in the present invention. Specific examples of commercially available water-based resins include water dispersibility such as “Acryset” (trade name; manufactured by Nippon Shokubai Co., Ltd.) and “Alloron” (trade name; manufactured by Nippon Shokubai Co., Ltd.). Or water-soluble acrylic resin; “Hydran” (trade name; manufactured by Dainippon Ink and Chemicals), “Bondic” (trade name; manufactured by Dainippon Ink and Chemicals), “Poise” (trade name) ; Kao Co., Ltd.), “Superflex” (trade name; Daiichi Kogyo Seiyaku Co., Ltd.), “Neolet” (trade name; manufactured by Zeneca Co., Ltd.), etc .; Water-based polyester such as Toyobo Co., Ltd.), "Finetex" (trade name; manufactured by Dainippon Ink & Chemicals, Inc.), etc .; Water dispersion such as "Horus" (trade name; manufactured by Kansai Paint Co., Ltd.) Water-diluted or water-soluble alkyd resin; Water dispersion, water dilution or water solubility of “Ban” (trade name; manufactured by Kuraray Isoprene Chemical Co., Ltd.), “Primacol” (manufactured by Dow Chemical Co., Ltd.), “Hi-Tech” (trade name; manufactured by Toho Chemical Co., Ltd.) Water-soluble epoxy resins such as “Epiclon” (trade name; manufactured by Dainippon Ink & Chemicals, Inc.); vinyl chloride emulsions; “Jurimer”, “Junron”, “Leogic”, “Aronbis” ( Water-dispersible or water-soluble acrylic resins such as trade name; manufactured by Nippon Pure Chemicals Co., Ltd., etc. are mentioned, but are not particularly limited.

  As specific examples, Acreset 19E, Acreset 210E, Acreset 260E, Acreset 288E, Alloron 453 (all manufactured by Nippon Shokubai Co., Ltd.), Sebian A-4635, 4718, 4601 (above, manufactured by Daicel Chemical Industries, Ltd.) ), Nipol Lx811, 814, 821, 820, 857 (manufactured by Nippon Zeon Co., Ltd.) and other water-dispersible or water-soluble acrylic resins; Sofranate AE-10, Sofuranate AE-40 (all Nippon Soflan Processing Manufactured), Hydran AP-10, 20, 30, 40, HW-110, Hydran HW-131, Hydran HW-135, Hydran HW-320, ECOS-3000, Bondic 2250, 72070 (all of which are Dainippon Ink Chemical Industries, Ltd.) (Made by Co., Ltd.), Poise 710, Poise 72 Water-dispersible polyurethane resins such as Mercury 525, Mercy 585, Mercy 414, and Mercy 455 (all manufactured by Toyo Polymer Co., Ltd.); Vironal MD-1200, Vironal MD-1400, Vironal MD-1930 (all manufactured by Toyobo Co., Ltd.), WD-size, WMS, WD3652, WJL6342 (all manufactured by Eastman Chemical Co., Ltd.), FINETEX ES650, 611, 675, 850 (above Dainippon Ink Chemical Co., Ltd.) Water-dispersible polyester resins such as Isoban-10, Isoban-06, Isoban-04 (all manufactured by Kuraray Isoprene Chemical Co., Ltd.), Primacol 5981, Primacol 5983, Primacol 5990, Primacol 5991 (any) Mow Dow Chemical ), Chemipearl S120, SA100 (Mitsui Petrochemical Co., Ltd.) and other water-soluble, water-dilutable or water-dispersible polyolefin resins, Jurimer AC-103, 10S, AT-510, ET-410, SEK -301, FC-60, SP-50TF, SPO-602, AC-70N (all manufactured by Nippon Pure Chemical), water dispersible or water-soluble acrylic resin, LACSTAR 7310K, 3307B, 4700H, 7132C (above Dainippon Ink Chemical Co., Ltd.), water-dispersible rubbers such as Nipol Lx416, 410, 438C, and 2507 (manufactured by Nippon Zeon Co., Ltd.), and water dispersibility such as G351 and G576 (manufactured by Nippon Zeon Co., Ltd.) Poly (vinyl chloride) s, poly (vinylidene chloride) s such as L502, L513 (manufactured by Asahi Kasei Kogyo Co., Ltd.), etc. It can be mentioned.

5) Others From the viewpoint of applicability, it is preferred that the hydrophilic polymer 2 containing layer gels due to a decrease in temperature. Since the fluidity of the layer formed by coating is lost by gelling, the surface of the image forming layer is less affected by wind for drying in the drying step after the coating step, A photothermographic material having a uniform coated surface can be obtained. It is preferable to add a gelling agent to the hydrophilic polymer 2 containing layer coating solution in order to obtain a coating solution that gels when the temperature decreases.

  Here, at the time of application, it is important that the coating solution is not gelled. Considering easiness of work, the coating liquid has fluidity at the time of coating, and gelates and loses fluidity at the time before entering the drying process after coating. The viscosity of the hydrophilic polymer 2-containing layer coating solution during coating is preferably 5 mPa · s or more and 200 mPa · s or less, and more preferably 10 mPa · s or more and 100 mPa · s or less.

  In the present invention, the solvent of the coating solution is an aqueous solvent. The aqueous solvent is a mixture of water or water with 70% by mass or less of a water-miscible organic solvent. Examples of the water-miscible organic solvent include alcohols such as methyl alcohol, ethyl alcohol and propyl alcohol, cellosolvs such as methyl cellosolve, ethyl cellosolve and butyl cellosolve, ethyl acetate and dimethylformamide.

  Although it is difficult to measure the viscosity of the formed layer at the time before entering the drying step after coating (gelation at this time), it is generally not less than 200 mPa · s and not more than 5000 mPa · s, preferably 500 mPa -It is estimated that it is about s or more and 5000 mPa * s or less.

  The temperature for gelation is not particularly limited, but the gelling temperature is preferably around room temperature in consideration of the work efficiency of coating. Because it is a temperature at which the fluidity of the coating liquid can be easily increased so that it can be easily applied, and the fluidity can be maintained (that is, the elevated temperature is easily maintained). This is because the temperature is such that it can be easily cooled to lose the fluidity of the formed layer after coating. Specifically, the gelation temperature is preferably 0 ° C. or higher and 40 ° C. or lower, more preferably 0 ° C. or higher and 35 ° C. or lower.

  If the temperature of the coating solution at the time of application is set higher than the gelation temperature, there is no particular limitation, and if the cooling temperature after coating and before the drying step is set lower than the gelation temperature, there is no particular limitation. No. However, if the difference between the temperature of the coating liquid and the cooling temperature is set to be small, gelation starts during the coating process, resulting in problems such as being unable to apply uniformly. Further, if the temperature of the coating solution is set too high in order to increase these temperature differences, problems such as evaporation of the solvent of the coating solution and change in viscosity occur. Therefore, the temperature difference is preferably set to 5 ° C. or more and 50 ° C. or less, more preferably 10 ° C. or more and 40 ° C. or less.

(I) Gelling agent The gelling agent in the present invention is a substance that causes gelation of the solution when added to a hydrophilic polymer aqueous solution or a hydrophobic polymer latex aqueous solution that is not derived from animal protein in the present invention, or cooled, or Furthermore, it is a substance that causes gelation when used in combination with a gelation promoting substance. By causing gelation, the fluidity is significantly reduced.

  Specific examples of the gelling agent include the following water-soluble polysaccharides. That is, agar, κ-carrageenan, ι-carrageenan, alginic acid, alginate, agarose, furceleran, gellan gum, glucono delta lactone, azotobacter vineland gum, xanthan gum, pectin, guar gum, locust bean gum, tara gum, cassia gum, gluco It is at least one selected from mannan, gum tragacanth, karaya gum, pullulan, gum arabic, arabinogalactan, dextran, carboxymethylcellulose sodium salt, methylcellulose, silium sheet gum, starch, chitin, chitosan and curdlan.

  Examples of the substance that gels by cooling after being heated and dissolved include substances such as agar, carrageenan, and julan gum.

  Among these gelling agents, κ-carrageenan (eg: K-9F, manufactured by Taisho Co., Ltd .: Nitta Gelatin Co., Ltd .: K-15: K-21-24, I— 3), iota-carrageenan and agar are mentioned, and κ-carrageenan is particularly preferred.

  The gelling agent is 0.01% by mass or more and 10.0% by mass or less, preferably 0.02% by mass or more and 5.0% by mass or less, more preferably 0.05% by mass or more and 2.% by mass or more with respect to the binder polymer. It is preferable to use 0% by mass or less.

(Ii) Gelling accelerator The gelling agent is preferably used together with a gelling accelerator. The gelation accelerator in the present invention is a compound that promotes gelation by contact with the gelling agent, and its function is exhibited by a specific combination with the gelling agent. In the present invention, the following combinations can be used as the combination of the gelling agent and the gelation accelerator.

  1) Alkaline metal ions such as potassium, or alkaline earth metal ions such as calcium and magnesium as gelling accelerators, and carrageenan, alginate, gellan gum, azotobacter vineland gum, pectin, sodium carboxymethylcellulose as gelling agents Combination of salt etc.

  2) A combination of boric acid or other boron compounds as a gelling accelerator and guar gum, locust bean gum, tara gum, cassia gum or the like as a gelling agent.

  3) A combination of an acid or an alkali as a gelling accelerator and an alginate, glucomannan, pectin, chitin, chitosan, curdlan or the like as a gelling agent.

  4) A water-soluble polysaccharide that reacts with a gelling agent to form a gel is used as a gelation accelerator. Specifically, a combination using xanthan gum as the gelling agent, using cassia gum as the gelling agent, using carrageenan as the gelling agent, and using locust bean gum as the gelling agent can be exemplified.

The following a) -g) can be illustrated as a specific example of the combination of these gelling agents and gelation accelerators.
a) Combination of kappa-carrageenan and potassium b) Combination of iota-carrageenan and calcium c) Combination of ro-methoxyl pectin and calcium d) Combination of sodium alginate and calcium e) Combination of gellan gum and calcium f) Combination of gellan gum and acid g) Combination of Locust Bingham and Xanthan Gum A plurality of such combinations may be used simultaneously.

  These gelation accelerators may be added to the same layer to which the gelling agent is added, but it is preferable to add them to different layers and act. More preferably, it is added to a layer not directly adjacent to the layer to which the gelling agent is added. That is, it is more preferable to have a layer containing neither a gelling agent nor a gelling accelerator between a layer containing a gelling agent and a layer containing a gelling accelerator.

  The gelling accelerator is used in an amount of 0.1 to 200% by mass, preferably 1.0 to 100% by mass, based on the gelling agent.

  In addition, additives can be appropriately added to the hydrophilic polymer 2-containing layer. Examples of such additives include surfactants, pH adjusters, preservatives, antifungal agents, dyes, pigments, and color tone adjusters.

(4) Hydrophobic polymer-containing layer In the present invention, the hydrophobic polymer-containing layer refers to a layer containing a hydrophobic polymer. A preferable content of the hydrophobic polymer is 50% by mass or more and 100% by mass or less, and more preferably 50% by mass or more and 75% by mass or less.
The hydrophobic polymer-containing layer can be provided as a non-photosensitive intermediate layer and an outermost layer. Preferably, the outermost layer is provided. When the outermost layer is a hydrophobic polymer-containing layer, it is possible to suppress stickiness and reduce the change in image quality due to finger marks.

The hydrophobic polymer refers to a polymer having an equilibrium water content of 5% by mass or less at 25 ° C. and 60% RH. “Equilibrium moisture content at 25 ° C. and 60% RH” means the following equation using the mass W1 of the polymer in the humidity-controlled equilibrium under the atmosphere of 25 ° C. and 60% RH, Can be expressed as:
Equilibrium moisture content at 25 ° C. and 60% RH = {(W1−W0) / W0} × 100 (mass%)

  For the definition and measurement method of moisture content, for example, Polymer Engineering Course 14, Polymer Material Testing Method (Edited by Society of Polymer Sciences, Jinshokan) can be referred to.

  The equilibrium moisture content at 25 ° C. and 60% RH of the binder polymer in the present invention is preferably 2% by mass or less, more preferably 0.01% by mass or more and 1.5% by mass or less, and further preferably 0.02% by mass. The content is preferably 1% by mass or less.

  In the present invention, the preferred glass transition temperature of the hydrophobic polymer is 0 ° C. or more and 80 ° C. or less, more preferably 10 ° C. or more and 70 ° C. or less, and further preferably 15 ° C. or more and 60 ° C. or less.

In this specification, Tg was calculated by the following formula.
1 / Tg = Σ (Xi / Tgi)
Here, it is assumed that n monomer components from i = 1 to n are copolymerized in the polymer. Xi is the mass fraction of the i-th monomer (ΣXi = 1), and Tgi is the glass transition temperature (absolute temperature) of the homopolymer of the i-th monomer. However, Σ is the sum from i = 1 to n.
In addition, the value (Tgi) of the homopolymer glass transition temperature of each monomer employ | adopted the value of Polymer Handbook (3rd Edition) (J. Brandrup, EH Immergut (Wiley-Interscience, 1989)).

Specific examples of the hydrophobic polymer that can be used for the hydrophobic polymer-containing layer include the latex that can be used for the non-photosensitive intermediate layer A of the present invention, polyacrylate, polyurethane, polymethacrylate, or a copolymer containing these. Polymer latex and the like can be mentioned.
Two or more binders may be used in combination as required. Further, a glass transition temperature of 20 ° C. or higher and a glass transition temperature of less than 20 ° C. may be used in combination. When two or more kinds of polymers having different Tg are blended, the mass average Tg is preferably within the above range.

In this invention, it is preferable to apply | coat and dry using the coating liquid whose 30 mass% or more of a solvent is water, and to form a hydrophobic polymer content layer.
A preferred form is one prepared so that the ionic conductivity is 2.5 mS / cm or less, and examples of such a preparation method include a purification method using a separation functional membrane after polymer synthesis.

  The coating solvent is preferably water or a mixture of 70% by mass or less of a water-miscible organic solvent in water. Examples of the water-miscible organic solvent include alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol, cellosolvs such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve, ethyl acetate, and dimethylformamide.

  In the present invention, a polymer dispersible in an aqueous solvent is particularly preferred. Examples of the dispersed state may be either latex in which fine particles of water-insoluble hydrophobic polymer are dispersed or polymer molecules dispersed in a molecular state or forming micelles. preferable. The average particle size of the dispersed particles is 1 nm or more and 50000 nm or less, preferably 5 nm or more and 1000 nm or less, more preferably 10 nm or more and 500 nm or less, and further preferably 50 nm or more and 200 nm or less. The particle size distribution of the dispersed particles is not particularly limited, and may have a wide particle size distribution or a monodispersed particle size distribution. Mixing two or more types having a monodispersed particle size distribution is also a preferable method for controlling the physical properties of the coating solution.

  Preferred embodiments of the hydrophobic polymer include acrylic polymers, poly (esters), rubbers (eg, SBR resin), poly (urethanes), poly (vinyl chloride) s, poly (vinyl acetate) s, poly (chloride chloride). Hydrophobic polymers such as vinylidene) and poly (olefin) s can be preferably used. These polymers may be linear polymers, branched polymers, crosslinked polymers, so-called homopolymers obtained by polymerizing a single monomer, or copolymers obtained by polymerizing two or more types of monomers. In the case of a copolymer, it may be a random copolymer or a block copolymer. The molecular weight of these polymers is 5,000 to 1,000,000, preferably 10,000 to 200,000 in terms of number average molecular weight. When the molecular weight is too small, the mechanical strength of the image forming layer is insufficient, and when the molecular weight is too large, the film formability is poor, which is not preferable. A crosslinkable polymer latex is particularly preferably used.

1) Specific Examples of Latex Specific examples of the preferred polymer latex include the following. Below, it represents using a raw material monomer, the numerical value in a parenthesis is the mass%, and molecular weight is a number average molecular weight. When a polyfunctional monomer was used, the concept of molecular weight was not applicable because a crosslinked structure was formed, so it was described as crosslinkability, and the description of molecular weight was omitted. Tg represents the glass transition temperature.

NP-1; -MMA (70) -EA (27) -MAA (3)-latex (molecular weight 37000, Tg 61 ° C.)
NP-2; latex of -MMA (70) -2EHA (20) -St (5) -AA (5)-(molecular weight 40000, Tg 59 ° C.)
-NP-3; latex of -St (50) -Bu (47) -MAA (3)-(crosslinkability, Tg-17 ° C)
-NP-4; -St (68) -Bu (29) -AA (3)-latex (crosslinkable, Tg 17 ° C)
NP-5; Latex of -St (71) -Bu (26) -AA (3)-(crosslinkability, Tg 24 ° C.)
NP-6; Latex (crosslinkable) of -St (70) -Bu (27) -IA (3)-
NP-7; latex of -St (75) -Bu (24) -AA (1)-(crosslinkability, Tg 29 ° C.)
NP-8; Latex (crosslinkable) of -St (60) -Bu (35) -DVB (3) -MAA (2)-
NP-9; Latex (crosslinkable) of -St (70) -Bu (25) -DVB (2) -AA (3)-
NP-10; latex of VC (50) -MMA (20) -EA (20) -AN (5) -AA (5)-(molecular weight 80,000)
-NP-11; -VDC (85) -MMA (5) -EA (5) -MAA (5)-latex (molecular weight 67000)
NP-12; -Et (90) -MAA (10)-latex (molecular weight 12000)
NP-13; -St (70) -2EHA (27) -AA (3) latex (molecular weight 130,000, Tg 43 ° C.)
NP-14; latex of MMA (63) -EA (35) -AA (2) (molecular weight 33000, Tg 47 ° C.)
-NP-15; -St (70.5) -Bu (26.5) -AA (3) -latex (crosslinkability, Tg 23 ° C.)
NP-16; latex of -St (69.5) -Bu (27.5) -AA (3)-(crosslinkability, Tg 20.5 ° C)
-NP-17; latex of -St (61.3) -isoprene (35.5) -AA (3)-(crosslinkability, Tg17 ° C)
NP-18; latex of -St (67) -isoprene (28) -Bu (2) -AA (3)-(crosslinkability, Tg 27 ° C.)

  The abbreviations for the above structures represent the following monomers. MMA; Methyl methacrylate, EA; Ethyl acrylate, MAA; Methacrylic acid, 2EHA; 2-Ethylhexyl acrylate, St; Styrene, Bu; Butadiene, AA; Acrylic acid, DVB; Divinylbenzene, VC; Vinyl chloride, AN; Acrylonitrile, VDC Vinylidene chloride, Et; ethylene, IA; itaconic acid.

  The polymer latex described above is also commercially available, and the following polymers can be used. Examples of the acrylic polymer include Sebian A-4635, 4718, 4601 (manufactured by Daicel Chemical Industries, Ltd.), Nipol Lx811, 814, 821, 820, 857 (manufactured by Nippon Zeon Co., Ltd.), etc. Examples of poly (esters) include poly (urethane) such as FINETEX ES650, 611, 675, 850 (above, manufactured by Dainippon Ink Chemical Co., Ltd.), WD-size, WMS (above, manufactured by Eastman Chemical). Examples of rubbers include HYDRAN AP10, 20, 30, 40 (manufactured by Dainippon Ink Chemical Co., Ltd.), and examples of rubbers include LACSTAR 7310K, 3307B, 4700H, 7132C (above, Dainippon Ink Chemical Co., Ltd.). (Made by Co., Ltd.), Nipol Lx416, 410, 438C, 2507 (above, Nippon Zeo) As examples of poly (vinyl chloride) such as G351 and G576 (above, manufactured by Nippon Zeon Co., Ltd.), examples of poly (vinylidene chloride) such as L502, L513 (above Examples of poly (olefin) s such as Asahi Kasei Kogyo Co., Ltd. include Chemipearl S120 and SA100 (above Mitsui Petrochemical Co., Ltd.).

  These polymer latexes may be used alone or in combination of two or more as required.

2) Preferred Latex The polymer latex used in the hydrophobic polymer layer of the present invention is particularly preferably an acrylic polymer copolymer, polyester, polyurethane or the like. Moreover, it is preferable that the polymer latex used for the hydrophobic polymer layer of this invention contains 1-6 mass% of acrylic acid or methacrylic acid, More preferably, it contains 2-5 mass%. The polymer latex used in the hydrophobic polymer layer of the present invention preferably contains acrylic acid.

3) coating amount of the coating weight hydrophobic polymer (per support 1 m ²⁾ is, 0.1 g / m ² or more 10 g / m ² or less is preferable, 0.3 g / m ² or more 5 g / m ² or less is more preferable.
The concentration in the coating solution is preferably adjusted so that the viscosity becomes a value suitable for simultaneous multilayer coating when added, but is not particularly limited. In general, the concentration in the liquid is 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 40% by mass or less, and particularly preferably 15% by mass or more and 30% by mass or less.

4) Polymer that can be used in combination In the hydrophobic polymer-containing layer, a hydrophobic polymer may be used alone, or two or more types may be used in combination. Further, a binder other than the hydrophobic polymer may be used in combination. When the polymer used in combination is a hydrophilic polymer, the hydrophilic polymer 1 or the hydrophilic polymer 2 in the present invention can be used.

  If necessary, a hydrophilic polymer such as gelatin, polyvinyl alcohol, methylcellulose, hydroxypropylcellulose, carboxymethylcellulose may be added to the hydrophobic polymer-containing layer of the photothermographic material of the invention. The addition amount of these hydrophilic polymers is preferably 30% by mass or less, more preferably 20% by mass or less, based on the total binder in the hydrophobic polymer-containing layer.

5) Crosslinking agent In the present invention, it is preferable to add a crosslinking agent to the hydrophobic polymer-containing layer. By adding, the hydrophobicity and water resistance of the non-photosensitive intermediate layer are increased, and an excellent photothermographic material is obtained. Preferred crosslinking agents are the same as those described for the non-photosensitive intermediate layer A.

6) Thickener It is preferable to add a thickener to the coating solution for forming the hydrophobic polymer-containing layer. It is preferable to add a thickener since a hydrophobic layer having a uniform thickness can be formed. Preferred thickeners are the same as those described for the non-photosensitive intermediate layer A.

  Various other additives can be added to the hydrophobic polymer-containing layer. For example, surfactants, pH adjusters, preservatives, antifungal agents and the like can be mentioned as additives.

(5) Outermost layer As the outermost layer of the present invention, any of the hydrophilic polymer 1-containing layer, the hydrophilic polymer 2-containing layer, and the hydrophobic polymer-containing layer may be used. Here, since the outermost layer is a part that is directly affected by the external environment during transportation, storage, or development, it is preferable to add the following as additives. These additives can be added to a layer other than the outermost layer, for example, a surface protective layer, an intermediate layer, a back layer, or a back surface protective layer that is not the outermost layer.

1) Matting Agent In the present invention, it is preferable to add a matting agent for improving the transportability. The matting agent is described in paragraph Nos. 0126 to 0127 of JP-A No. 11-65021. The matting agent is preferably 1 mg / m ² or more and 400 mg / m ² or less, more preferably 5 mg / m ² or more and 300 mg / m ² or less when expressed in terms of the coating amount per 1 m ^{2 of the} photothermographic material.
In the present invention, the shape of the matting agent may be either a regular shape or an irregular shape, but is preferably a regular shape, and a spherical shape is preferably used.
The volume weighted average of the equivalent sphere diameters of the matting agent used for the image forming layer surface is preferably from 0.3 μm to 10 μm, and more preferably from 0.5 μm to 7 μm. Further, the variation coefficient of the size distribution of the matting agent is preferably 5% or more and 80% or less, and more preferably 20% or more and 80% or less. Here, the coefficient of variation is a value represented by (standard deviation of particle size) / (average value of particle size) × 100. Further, two or more kinds of matting agents having different average particle sizes can be used as the matting agent on the image forming layer surface. In this case, the difference in particle size between the matting agent having the largest average particle size and the smallest matting agent is preferably 2 μm or more and 8 μm or less, and more preferably 2 μm or more and 6 μm or less.
The volume weighted average of the equivalent sphere diameters of the matting agent used for the back surface is preferably 1 μm or more and 15 μm or less, and more preferably 3 μm or more and 10 μm or less. The variation coefficient of the size distribution of the matting agent is preferably 3% or more and 50% or less, and more preferably 5% or more and 30% or less. Further, two or more kinds of matting agents having different average particle sizes can be used as the matting agent for the back surface. In that case, the difference in particle size between the matting agent having the largest average particle size and the smallest matting agent is preferably 2 μm or more and 14 μm or less, and more preferably 2 μm or more and 9 μm or less.

  The matting degree of the image forming layer surface may be any as long as no stardust failure occurs, but the Beck smoothness is preferably 30 seconds or more and 2000 seconds or less, particularly preferably 40 seconds or more and 1500 seconds or less. The Beck smoothness can be easily determined by Japanese Industrial Standard (JIS) P8119 “Smoothness test method using Beck tester for paper and paperboard” and TAPPI standard method T479.

  In the present invention, the matte degree of the back layer is preferably a Beck smoothness of 1200 seconds or less and 10 seconds or more, preferably 800 seconds or less and 20 seconds or more, and more preferably 500 seconds or less and 40 seconds or more.

  In the present invention, the matting agent is preferably contained in a layer functioning as the outermost layer or surface protective layer of the photothermographic material or a layer close to the outermost layer.

2) Sliding agent It is preferable to use a sliding agent such as liquid paraffin, long-chain fatty acid, fatty acid amide, and fatty acid ester in order to improve the handling property during production and the scratch resistance during heat development. In particular, liquid paraffin from which low-boiling components have been removed and fatty acid esters having a branched structure and having a molecular weight of 1000 or more are preferred.

As the slip agent, compounds described in paragraph No. 0117 of JP-A No. 11-65021, JP-A No. 2000-5137, JP-A No. 2004-219794, JP-A No. 2004-21802, and JP-A No. 2004-334077 are preferable.
The amount of the slip agent used is in the range of 1 mg / m ^{2 to} 200 mg / m ² , preferably 10 mg / m ^{2 to} 150 mg / m ² , more preferably 20 mg / m ^{2 to} 100 mg / m ^2. .

  The layer to which the slip agent is added may be either an image forming layer or a non-photosensitive layer, but it is preferably added to the outermost layer for the purpose of improving transportability and scratch resistance.

3) Surfactant As for the surfactant applicable to the present invention, paragraph No. 0132 of JP-A No. 11-65021, paragraph No. 0133 of the solvent, paragraph No. 0134 of the support, and antistatic or conductive layer Are described in paragraph No. 0135 of the same number, paragraph No. 0136 of the same number about the method of obtaining a color image, paragraph numbers 0061 to 0064 of JP-A No. 11-84573 and paragraph numbers 0049 to 0062 of JP-A No. 2001-83679 about the slip agent. ing.
In the present invention, it is preferable to use a fluorosurfactant. Specific examples of the fluorosurfactant include compounds described in JP-A Nos. 10-197985, 2000-19680, 2000-214554 and the like. In addition, a polymeric fluorine-based surfactant described in JP-A-9-281636 is also preferably used. In the photothermographic material of the present invention, it is preferable to use fluorine-based surfactants described in JP-A Nos. 2002-82411, 2003-057780, and 2003-149766. In particular, the fluorosurfactants described in JP-A-2003-057780 and JP-A-2001-264110 are preferable in terms of charge adjustment ability, stability of the coated surface, and smoothness when coating and production is performed with an aqueous coating solution. The fluorine-based surfactant described in JP-A No. 2001-264110 is most preferable because it has a high charge adjusting ability and requires a small amount of use.
In the present invention, the fluorosurfactant can be used on either the image forming layer surface or the back surface, and is preferably used on both surfaces. Further, it is particularly preferable to use in combination with a conductive layer containing the above-described metal oxide. In this case, sufficient performance can be obtained even if the amount of the fluorosurfactant used on the surface having the conductive layer is reduced or removed.
The preferred amount of the fluorocarbon surfactant is an image forming layer side, the range to the back surface each ^{0.1mg / m 2 ~100mg / m 2} , more preferably 0.3mg / m ² ~30mg / m ² range, even more preferably from ^{1mg / m 2 ~10mg / m 2} . In particular JP fluorocarbon surfactant described in JP-A No. 2001-264110 is effective, and preferably in the range of ^{0.01mg / m 2 ~10mg / m 2} , more in the range of 0.1mg / m ² ~5mg / m ² preferable.

(6) Image forming layer (Description of organic silver salt)
1) Composition The organic silver salt that can be used in the present invention is relatively stable to light, but is heated to 80 ° C. or higher in the presence of exposed photosensitive silver halide and a reducing agent. In this case, the silver salt functions as a silver ion supplier to form a silver image. The organic silver salt may be any organic substance that can supply silver ions that can be reduced by a reducing agent. Regarding such non-photosensitive organic silver salt, paragraph numbers 0048 to 0049 of JP-A-10-62899, page 18 line 24 to page 19 line 37 of European Patent Publication No. 0803764A1, European Patent Publication. No. 0968212A1, JP-A-11-349591, JP-A-2000-7683, JP-A-2000-72711, and the like. Silver salts of organic acids, particularly silver salts of long-chain aliphatic carboxylic acids (having 10 to 30, preferably 15 to 28 carbon atoms) are preferred. Preferable examples of the fatty acid silver salt include silver lignocerate, silver behenate, silver arachidate, silver stearate, silver oleate, silver laurate, silver caproate, silver myristate, silver palmitate, silver erucate and the like. Including a mixture of In the present invention, among these fatty acid silvers, the silver behenate content is preferably 50 mol% to 100 mol%, more preferably 85 mol% to 100 mol%, and still more preferably 90 mol% to 100 mol%. The following fatty acid silver is preferably used.
Furthermore, it is preferable to use fatty acid silver having a silver erucate content of 2 mol% or less, more preferably 1 mol% or less, and still more preferably 0.1 mol% or less.

  Moreover, it is preferable that silver stearate content rate is 1 mol% or less. By setting the stearic acid content to 1 mol% or less, a silver salt of an organic acid having a low Dmin, high sensitivity and excellent image storage stability can be obtained. As said stearic acid content rate, 0.5 mol% or less is preferable and it is especially preferable not to contain substantially.

  Furthermore, when silver arachidate is included as the silver salt of the organic acid, the silver arachidate content is 6 mol% or less to obtain a low Dmin and an organic acid silver salt excellent in image storability. It is preferable at a point and it is still more preferable that it is 3 mol% or less.

2) Shape The shape of the organic silver salt that can be used in the present invention is not particularly limited, and may be any of a needle shape, a rod shape, a flat plate shape, and a flake shape.
In the present invention, scaly organic silver salts are preferred. In addition, short needle-like, rectangular parallelepiped, cubic or potato-like amorphous particles having a major axis / uniaxial length ratio of less than 5 are also preferably used. These organic silver particles have a feature that the fog at the time of heat development is less than that of long needle-like particles having a ratio of the long axis to the single axis of 5 or more. In particular, particles having a major axis / uniaxial ratio of 3 or less are preferable because the mechanical stability of the coating film is improved. In the present specification, the scaly organic silver salt is defined as follows. The organic acid silver salt was observed with an electron microscope, the shape of the organic acid silver salt particle was approximated to a rectangular parallelepiped, and the sides of the rectangular parallelepiped were designated a, b, and c from the shortest side (c was the same as b). Then, the shorter numerical values a and b are calculated, and x is obtained as follows.
x = b / a

  In this way, x is obtained for about 200 particles, and when the average value x (average) is obtained, particles satisfying the relationship of x (average) ≧ 1.5 are defined as flakes. Preferably, 30 ≧ x (average) ≧ 1.5, more preferably 15 ≧ x (average) ≧ 1.5. Incidentally, the needle shape is 1 ≦ x (average) <1.5.

  In the flake shaped particle, a can be regarded as a thickness of a tabular particle having a main plane with b and c as sides. The average of a is preferably 0.01 μm or more and 0.3 μm or less, and more preferably 0.1 μm or more and 0.23 μm or less. The average c / b is preferably 1 or more and 9 or less, more preferably 1 or more and 6 or less, still more preferably 1 or more and 4 or less, and most preferably 1 or more and 3 or less.

By setting the equivalent sphere diameter to 0.05 μm or more and 1 μm or less, aggregation is hardly caused in the photothermographic material, and image storability is improved. The sphere equivalent diameter is preferably 0.1 μm or more and 1 μm or less. In the present invention, the method for measuring the equivalent sphere diameter is obtained by directly photographing a sample using an electron microscope and then image-processing the negative.
In the flake shaped particles, the spherical equivalent diameter / a of the particles is defined as the aspect ratio. The aspect ratio of the scaly particles is preferably 1.1 or more and 30 or less, and preferably 1.1 or more and 15 or less, from the viewpoint of preventing aggregation in the photothermographic material and improving the image storage stability. More preferred.

  The particle size distribution of the organic silver salt is preferably monodispersed. Monodispersion is preferably 100% or less, more preferably 80% or less, and even more preferably 50% of the value obtained by dividing the standard deviation of the lengths of the short and long axes by the short and long axes. It is as follows. The method for measuring the shape of the organic silver salt can be determined from a transmission electron microscope image of the organic silver salt dispersion. As another method for measuring monodispersity, there is a method for obtaining the standard deviation of the volume weighted average diameter of the organic silver salt, and the percentage (variation coefficient) of the value divided by the volume weighted average diameter is preferably 100% or less, more Preferably it is 80% or less, More preferably, it is 50% or less. As a measuring method, for example, it is obtained from the particle size (volume weighted average diameter) obtained by irradiating an organic silver salt dispersed in a liquid with laser light and obtaining an autocorrelation function with respect to the temporal change of the fluctuation of the scattered light. Can do.

3) Preparation Known methods and the like can be applied to the production and dispersion method of the organic acid silver used in the present invention. For example, the above-mentioned JP-A-10-62899, European Patent Publication No. 0803763A1, European Patent Publication No. 0968212A1, JP-A-11-349591, JP-A-2000-7683, JP-A-2000-72711, JP-A-2001-163889, 2001-163890, 2001-163828, 2001-33907, 2001-188313, 2001-83651, 2002-6442, 2002-49117, 2002-31870, 2002-107868 You can refer to the issue.

  In addition, when the photosensitive silver salt is allowed to coexist at the time of dispersion of the organic silver salt, the fog rises and the sensitivity is remarkably lowered. Therefore, it is more preferable that the photosensitive silver salt is not substantially contained at the time of dispersion. In the present invention, the amount of the photosensitive silver salt in the aqueous dispersion to be dispersed is preferably 1 mol% or less, more preferably 0.1 mol% or less with respect to 1 mol of the organic acid silver salt in the liquid. Further, it is more preferable that no positive photosensitive silver salt is added.

  In the present invention, a photothermographic material can be produced by mixing an organic silver salt aqueous dispersion and a photosensitive silver salt aqueous dispersion, but the mixing ratio of the organic silver salt and the photosensitive silver salt can be selected according to the purpose. However, the ratio of the photosensitive silver salt to the organic silver salt is preferably in the range of 1 mol% to 30 mol%, more preferably 2 mol% to 20 mol%, and particularly preferably 3 mol% to 15 mol%. Mixing two or more organic silver salt aqueous dispersions and two or more photosensitive silver salt aqueous dispersions when mixing is a method preferably used for adjusting photographic characteristics.

4) Addition amount Although the organic silver salt in the present invention can be used in a desired amount, the total amount of coated silver including silver halide is preferably 0.1 g / m ² or more and 5.0 g / m ² or less, more preferably. It is 0.3 g / m ² or more and 3.0 g / m ² or less, more preferably 0.5 g / m ² or more and 2.0 g / m ² or less.
In particular, in order to improve image storability, the total coated silver amount is 1.8 g / m ² or less, more preferably 1.6 g / m ² or less, and still more preferably 1.3 g / m ² or less. preferable. If the preferred reducing agent in the present invention is used, a sufficient image density can be obtained even with such a low silver amount.

(Description of antifogging agent)
Antifogging agents, stabilizers and stabilizer precursors that can be used in the present invention are paragraph No. 0070 of JP-A No. 10-62899, European Patent Publication No. 0803764A, page 20, line 57 to page 21, line 7. And the compounds described in JP-A-9-281737 and JP-A-9-329864, and the compounds described in US Pat. No. 6,083,681 and European Patent 1048875.

(1) Description of Polyhalogen Compound Hereinafter, the organic polyhalogen compound which is a preferred antifogging agent that can be used in the present invention will be specifically described. In particular, in the present invention, the organic polyhalogen compound represented by the following general formula (H) is an image preservability (raw preservability) of an unexposed photosensitive material, especially preservation under high temperature conditions in a dark place. It is preferable from the viewpoint that the rise of fog caused by the can be improved.
General formula (H)
Q- (Y) n-C (Z ₁ ) (Z ₂ ) X
In general formula (H), Q represents an alkyl group, an aryl group or a heterocyclic group, Y represents a divalent linking group, n represents 0 to ₁ , Z ₁ and Z ₂ represent a halogen atom, X represents a hydrogen atom or an electron withdrawing group.

In the general formula (H), Q is preferably an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a heterocyclic group containing at least one nitrogen atom (pyridine, quinoline group, etc.).
In the general formula (H), when Q is an aryl group, Q preferably represents a phenyl group substituted with an electron-attracting group having a positive Hammett's substituent constant σp. For Hammett's substituent constants, see Journal of Medicinal Chemistry, 1973, Vol. 16, no. 11, 1207-1216 etc. can be referred to. Examples of such an electron withdrawing group include a halogen atom, an alkyl group substituted with an electron withdrawing group, an aryl group substituted with an electron withdrawing group, a heterocyclic group, an alkyl or arylsulfonyl group, acyl Group, alkoxycarbonyl group, carbamoyl group, sulfamoyl group and the like. Particularly preferred as the electron withdrawing group are a halogen atom, a carbamoyl group and an arylsulfonyl group, and a carbamoyl group is particularly preferred.

X is preferably an electron withdrawing group. Preferred electron withdrawing groups are halogen atoms, aliphatic / aryl or heterocyclic sulfonyl groups, aliphatic / aryl or heterocyclic acyl groups, aliphatic / aryl or heterocyclic oxycarbonyl groups, carbamoyl groups, sulfamoyl groups, More preferred are a halogen atom and a carbamoyl group, and particularly preferred is a bromine atom.
Z ₁ and Z ₂ are preferably a bromine atom or an iodine atom, and more preferably a bromine atom.
Y preferably represents -C (= O) -, - SO -, - SO 2 -, - C (= O) N (R) -, - SO 2 N (R) - , more preferably -C ( ═O) —, —SO ₂ —, —C (═O) N (R) —, and particularly preferably —SO ₂ —, —C (═O) N (R) —. R here represents a hydrogen atom, an aryl group or an alkyl group, more preferably a hydrogen atom or an alkyl group, and particularly preferably a hydrogen atom.
n represents 0 or 1, and is preferably 1.
In General Formula (H), when Q is an alkyl group, preferred Y is —C (═O) N (R) —, and when Q is an aryl group or a heterocyclic group, preferred Y is —SO ₂ —. is there.
In the general formula (H), a form in which residues obtained by removing a hydrogen atom from the compound are bonded to each other (generally referred to as bis type, tris type, tetrakis type) can also be preferably used.
In the general formula (H), a dissociable group (for example, a COOH group or a salt thereof, a SO ₃ H group or a salt thereof, a PO ₃ H group or a salt thereof), a group containing a quaternary nitrogen cation (for example, an ammonium group or a pyridinium group) Etc.), those having a polyethyleneoxy group, a hydroxyl group or the like as a substituent are also preferred.

  Specific examples of the compound represented by formula (H) in the present invention are shown below.

Further, when two or more compounds represented by the general formula (H) are used in combination, the above-mentioned unexposed photosensitive material can be preserved in the raw state, exposed to light, and image-preserved after heat development. Is preferable because it can be further improved. In the case of using together, it is preferable that the melting temperature of the mixture contained in the ratio of the content thereof is −10 ° C. or more and 50 ° C. or less with respect to the heat development temperature. When the heat development temperature is 120 ° C., preferred combinations of the compounds represented by the general formula (H) are (H-5) and (H-1) (129 ° C., the difference is 9 ° C.), (H -2) and (H-5) (154 ° C, difference is 34 ° C), (H-1) and (H-4) (122 ° C, difference is 2 ° C), (H-2) and (H-4) ) (132 ° C., difference is 12 ° C.), (H-4) and (H-5) (129 ° C., difference is 9 ° C.), etc., but are not limited thereto.
When two or more compounds represented by formula (H) are used in combination, the total of the two or more compounds is 1 × 10 ⁻⁶ mol / m ² to 1 × 10 ⁻⁶ mol / m ² as the coating amount per 1 m ^{2 of} heat-developable image recording material. 1 × 10 ⁻² mol / m ² is preferable, more preferably 1 × 10 ⁻⁵ mol / m ^{2 to} 5 × 10 ⁻³ mol / m ² , and still more preferably 2 × 10 ⁻⁵ mol / m ² to 2 × 10 ⁻³ mol / m ² . The ratio (molar ratio) of the combination of the compounds represented by the general formula (H) is not particularly limited. For example, when two compounds represented by the general formula (H) are used, for example, 0.5: 99 It can be made into arbitrary ratios in the range of 0.5-99.5: 0.5. When three or more compounds represented by general formula (H) are used, the total molar ratio of the remaining compounds represented by general formula (H) excluding the compound having the highest molar ratio is 0.5% or more. It can be.

  Polyhalogen compounds that can be used in the present invention other than those described above include US Pat. No. 3,874,946, US Pat. No. 4,756,999, US Pat. No. 5,340,712, US Pat. No. 5,346,737, US Pat. No. 5,466,537, JP-A-50-137126, US Pat. 119624, 59-57234, JP-A-7-2781, 7-5621, 9-160164, 9-244177, 9-244178, 9-160167, 9- 319022, 9-258367, 9-265150, 9-319022, 10-197988, 10-197989, 11-242304, JP 2000-2963, JP 2000-11270 , JP2000-284410, JP2 The compounds listed as exemplary compounds of the invention in 00-284212, JP-A-2001-33911, JP-A-2001-31644, JP-A-2001-312027, and JP-A-2003-50441 are preferably used. In particular, compounds specifically exemplified in JP-A-7-2781, JP-A-2001-33911, and JP-A-2001-312027 are preferred.

In the present invention, the polyhalogen compound is preferably used in the range of 10 ⁻⁴ mol to 1 mol, more preferably 10 ⁻³ mol to 0.5 mol, per mol of the non-photosensitive silver salt. It is preferable to use in the range of 1 × 10 ⁻² mol or more and 0.2 mol or less.

  In the present invention, examples of the method for incorporating the antifoggant into the photothermographic material include the methods described in the method for containing a reducing agent, and the organic polyhalogen compound is also preferably added as a solid fine particle dispersion.

(2) Other antifogging agents Other antifogging agents include mercury (II) salts described in paragraph No. 0113 of JP-A No. 11-65021, benzoic acids of paragraph No. 0114 of the same, salicylic acid derivatives disclosed in JP-A No. 2000-206642, Formalin scavenger compound represented by formula (S) of JP-A No. 2000-221634, triazine compound according to claim 9 of JP-A No. 11-352624, and general formula (III) of JP-A No. 6-11791 Examples thereof include 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene and the like.

The photothermographic material in the invention may contain an azolium salt for the purpose of preventing fogging. Examples of the azolium salt include compounds represented by general formula (XI) described in JP-A-59-193447, compounds described in JP-B-55-12581, and general formula (II) described in JP-A-60-153039. And the compounds represented. The azolium salt may be added to any part of the light-sensitive material, but the addition layer is preferably added to the layer having the image forming layer, and more preferably added to the image forming layer. The azolium salt may be added at any step during the preparation of the coating solution, and when added to the image forming layer, any step from the preparation of the organic silver salt to the preparation of the coating solution may be used. Immediately before is preferable. The azolium salt may be added by any method such as powder, solution, fine particle dispersion. Moreover, you may add as a solution mixed with other additives, such as a sensitizing dye, a reducing agent, and a color toning agent. In the present invention, the azolium salt may be added in any amount, but it is preferably 1 × 10 ⁻⁶ mol or more and 2 mol or less, more preferably 1 × 10 ⁻³ mol or more and 0.5 mol or less per 1 mol of silver.

(Description of reducing agent)
The photothermographic material of the present invention preferably contains a reducing agent for organic silver salt. The reducing agent for the organic silver salt may be any substance (preferably an organic substance) that reduces silver ions to metallic silver. Examples of such reducing agents are described in JP-A No. 11-65021, paragraphs 0043 to 0045, and European Patent Publication No. 0803764A1, page 7, line 34 to page 18, line 12.
In the present invention, the reducing agent is preferably a so-called hindered phenol reducing agent or bisphenol reducing agent having a substituent at the ortho position of the phenolic hydroxyl group. In particular, in the present invention, a compound represented by the following general formula (R) is preferable.

In the general formula (R), R ¹¹ and R ¹¹ ′ each independently represents an alkyl group having 1 to 20 carbon atoms. R ¹² and R ¹² ′ each independently represent a hydrogen atom or a substituent that can be substituted on a benzene ring. L represents a —S— group or a —CHR ¹³ — group. R ¹³ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. X ¹ and X ¹ ′ each independently represent a hydrogen atom or a group that can be substituted on a benzene ring.

The general formula (R) will be described in detail.
In the following, when referred to as an alkyl group, a cycloalkyl group is also included in this unless otherwise specified.
1) R ¹¹ and R ¹¹ '
R ¹¹ and R ¹¹ ′ are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms. The substituent of the alkyl group is not particularly limited, but preferably an aryl group, a hydroxy group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acylamino group, a sulfonamido group, a sulfonyl group, a phosphoryl group, Examples include an acyl group, a carbamoyl group, an ester group, a ureido group, a urethane group, and a halogen atom.

2) R ¹² and R ¹² ', X ¹ and X ¹ '
R ¹² and R ¹² ′ each independently represent a hydrogen atom or a substituent capable of substituting for a benzene ring, and X ¹ and X ¹ ′ each independently represent a hydrogen atom or a group capable of substituting for a benzene ring. Preferred examples of each group that can be substituted on the benzene ring include alkyl groups, aryl groups, halogen atoms, alkoxy groups, and acylamino groups.

3) L
L represents a —S— group or a —CHR ¹³ — group. R ¹³ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and the alkyl group may have a substituent. Specific examples of the unsubstituted alkyl group of R ¹³ are methyl group, ethyl group, propyl group, butyl group, heptyl group, undecyl group, isopropyl group, 1-ethylpentyl group, 2,4,4-trimethylpentyl group, cyclohexyl. Group, 2,4-dimethyl-3-cyclohexenyl group, 3,5-dimethyl-3-cyclohexenyl group and the like. Examples of the substituent of the alkyl group are the same as the substituent of R ¹¹ , and are a halogen atom, alkoxy group, alkylthio group, aryloxy group, arylthio group, acylamino group, sulfonamido group, sulfonyl group, phosphoryl group, oxycarbonyl group, Examples thereof include a carbamoyl group and a sulfamoyl group.

4) Preferred substituents R ¹¹ and R ¹¹ ′ are preferably a primary, secondary or tertiary alkyl group having 1 to 15 carbon atoms, specifically a methyl group, an isopropyl group, a t-butyl group, Examples thereof include a t-amyl group, a t-octyl group, a cyclohexyl group, a cyclopentyl group, a 1-methylcyclohexyl group, and a 1-methylcyclopropyl group. R ¹¹ and R ¹¹ ′ are more preferably an alkyl group having 1 to 4 carbon atoms, and among them, a methyl group, a t-butyl group, a t-amyl group, or a 1-methylcyclohexyl group is more preferable, and a methyl group, t- A butyl group is most preferred.

R ¹² and R ¹² ′ are preferably an alkyl group having 1 to 20 carbon atoms, specifically a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, a t-butyl group, a t-amyl group, Examples include a cyclohexyl group, 1-methylcyclohexyl group, benzyl group, methoxymethyl group, and methoxyethyl group. More preferred are a methyl group, an ethyl group, a propyl group, an isopropyl group, or a t-butyl group, and particularly preferred are a methyl group and an ethyl group.
X ¹ and X ¹ ′ are preferably a hydrogen atom, a halogen atom, or an alkyl group, and more preferably a hydrogen atom.

L is preferably a —CHR ¹³ — group.
R ¹³ is preferably a hydrogen atom or an alkyl group having 1 to 15 carbon atoms. As the alkyl group, a cyclic alkyl group is also preferably used in addition to a chain alkyl group. Moreover, what has a C = C bond in these alkyl groups can also be used preferably. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a 2,4,4-trimethylpentyl group, a cyclohexyl group, a 2,4-dimethyl-3-cyclohexenyl group, or 3,5-dimethyl-3. -A cyclohexenyl group and the like are preferable. R ¹³ is particularly preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, or a 2,4-dimethyl-3-cyclohexenyl group.

When R ¹¹ and R ¹¹ ′ are tertiary alkyl groups and R ¹² and R ¹² ′ are methyl groups, R ¹³ is a primary or secondary alkyl group having 1 to 8 carbon atoms (methyl group, ethyl group, propyl group). Group, isopropyl group, or 2,4-dimethyl-3-cyclohexenyl group).
When R ¹¹ and R ¹¹ ′ are tertiary alkyl groups and R ¹² and R ¹² ′ are alkyl groups other than methyl groups, R ¹³ is preferably a hydrogen atom.
When R ¹¹ and R ¹¹ ′ are not a tertiary alkyl group, R ¹³ is preferably a hydrogen atom or a secondary alkyl group, and particularly preferably a secondary alkyl group. Preferred groups as the secondary alkyl group for R ¹³ are isopropyl group and 2,4-dimethyl-3-cyclohexenyl group.
The reducing agent has different heat developability and developed silver tone depending on the combination of R ¹¹ , R ¹¹ ′, R ¹² , R ¹² ′ and R ¹³ . Since these can be adjusted by combining two or more reducing agents, it is preferable to use a combination of two or more depending on the purpose.
In the present invention, a reducing agent represented by the following general formula (R1) is preferable.

In the general formula (R1), portions different from the general formula (R) are R ¹¹ and R ¹¹ ′. R ¹¹ and R ¹¹ ′ each independently represents a secondary or tertiary alkyl group having 1 to 15 carbon atoms. R ¹² , R ¹² ′, L, X ¹ and X ¹ ′ are the same as in the case of the general formula (R).

  Although the specific example of the reducing agent in this invention including the compound represented by general formula (R) below is shown, this invention is not limited to these.

  Examples of preferable reducing agents in the present invention other than the above are the compounds described in JP-A Nos. 2001-188314, 2001-209145, 2001-350235, 2002-156727, and EP1278101A2.

In the present invention, the addition amount of the reducing agent is preferably 0.1 g / m ² or more and 3.0 g / m ² or less, more preferably 0.2 g / m ² or more and 2.0 g / m ² as a whole. In the following, it is more preferably 0.3 g / m ² or more and 1.0 g / m ² or less. 5 mol% or more and 50 mol% or less is preferably contained with respect to 1 mol of silver on the surface having the image forming layer, more preferably 8 mol% or more and 30 mol% or less, and 10 mol% or more and 20 mol% or less. More preferably, it is contained.

The reducing agent may be contained in the coating solution by any method such as a solution form, an emulsified dispersion form, or a solid fine particle dispersion form, and may be contained in the photothermographic material.
Well-known emulsification and dispersion methods include oils such as dibutyl phthalate, tricresyl phosphate, dioctyl sebacate or tri (2-ethylhexyl) phosphate, and an auxiliary solvent such as ethyl acetate and cyclohexanone, and dodecylbenzene. Examples thereof include a method of mechanically preparing an emulsified dispersion by adding a surfactant such as sodium sulfonate, oleoyl-N-methyl taurate, sodium di (2-ethylhexyl) sulfosuccinate. At this time, it is also preferable to add a polymer such as α-methylstyrene oligomer or poly (t-butylacrylamide) for the purpose of adjusting the viscosity and refractive index of the oil droplets.

Further, as a solid fine particle dispersion method, a reducing agent powder is dispersed in an appropriate solvent such as water by a ball mill, a colloid mill, a vibration ball mill, a sand mill, a jet mill, a roller mill, or an ultrasonic wave to produce a solid dispersion. A method is mentioned. In this case, a protective colloid (for example, polyvinyl alcohol) or a surfactant (for example, an anionic surfactant such as sodium triisopropylnaphthalenesulfonate (a mixture of three isopropyl groups having different substitution positions)) may be used. Good. In the mills, beads such as zirconia are usually used as a dispersion medium, and Zr and the like eluted from these beads may be mixed in the dispersion. Although it depends on the dispersion conditions, it is usually in the range of 1 ppm to 1000 ppm. If the Zr content in the light-sensitive material is 0.5 mg or less per 1 g of silver, there is no practical problem.
The aqueous dispersion preferably contains a preservative (for example, benzoisothiazolinone sodium salt).
Particularly preferred is a solid particle dispersion method of a reducing agent, which is added as fine particles having an average particle size of 0.01 μm to 10 μm, preferably 0.05 μm to 5 μm, more preferably 0.1 μm to 2 μm. Is preferred. In the present application, it is preferable to use other solid dispersions dispersed in a particle size within this range.

(Description of development accelerator)
In the present invention, it is preferable to add a development accelerator.
In the photothermographic material of the present invention, a sulfonamide phenol compound represented by the general formula (A) described in JP-A-2000-267222, JP-A-2000-330234, or the like as a development accelerator, Hindered phenol compounds represented by general formula (II) described in JP-A No. 2001-92075, general formula (I) described in JP-A No. 10-62895, JP-A No. 11-15116 and the like, A hydrazine-based compound represented by general formula (D) of JP-A No. 2002-156727 or general formula (1) described in JP-A No. 2002-278017, and described in JP-A No. 2001-264929 Phenol-based or naphthol-based compounds represented by the general formula (2) are preferably used. Moreover, the phenol type compound described in Unexamined-Japanese-Patent No. 2002-311533 and Unexamined-Japanese-Patent No. 2002-341484 is also preferable. In particular, naphthol compounds described in JP-A-2003-66558 are preferred.

  In the present invention, the development accelerator is used in the range of 0.1 mol% or more and 20 mol% or less, preferably 0.5 mol% or more and 10 mol% or less, more preferably, relative to the reducing agent. It is used in the range of 1 mol% or more and 5 mol% or less.

The introduction method to the light-sensitive material includes the same method as the reducing agent, but it is particularly preferable to add as a solid dispersion or an emulsified dispersion. When added as an emulsified dispersion, it is added as an emulsified dispersion dispersed using a high-boiling solvent and a low-boiling auxiliary solvent that are solid at room temperature, or as a so-called oilless emulsified dispersion that does not use a high-boiling solvent. It is preferable to add.
In the present invention, among the above development accelerators, hydrazine compounds described in JP-A Nos. 2002-156727 and 2002-278017 and naphthol compounds described in JP-A No. 2003-66558 are used. Is more preferable.

Particularly preferred development accelerators in the invention are compounds represented by the following general formulas (A-1) and (A-2).
Formula (A-1); Q ₁ -NHNH-Q ₂
In formula (I), Q ₁ represents an aromatic group or a heterocyclic group which bonds to -NHNH-Q ₂ at a carbon atom. Q ₂ represents a carbamoyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a sulfonyl group, or a sulfamoyl group.

In the general formula (A-1), the aromatic group or heterocyclic group represented by Q ₁ is preferably a 5- to 7-membered unsaturated ring. Preferred examples include benzene ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, 1,2,4-triazine ring, 1,3,5-triazine ring, pyrrole ring, imidazole ring, pyrazole ring, 1,2 , 3-triazole ring, 1,2,4-triazole ring, tetrazole ring, 1,3,4-thiadiazole ring, 1,2,4-thiadiazole ring, 1,2,5-thiadiazole ring, 1,3,4 -Oxadiazole ring, 1,2,4-oxadiazole ring, 1,2,5-oxadiazole ring, thiazole ring, oxazole ring, isothiazole ring, isoxazole ring, or thiophene ring are preferred, A condensed ring in which these rings are condensed with each other is also preferable.

  These rings may have a substituent, and when they have two or more substituents, these substituents may be the same or different. Examples of substituents include halogen atoms, alkyl groups, aryl groups, carbonamido groups, alkylsulfonamido groups, arylsulfonamido groups, alkoxy groups, aryloxy groups, alkylthio groups, arylthio groups, carbamoyl groups, sulfamoyl groups, cyano Groups, alkylsulfonyl groups, arylsulfonyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, and acyl groups. When these substituents are substitutable groups, they may further have substituents. Examples of preferred substituents include halogen atoms, alkyl groups, aryl groups, carbonamido groups, alkylsulfonamido groups, aryls. Sulfonamide group, alkoxy group, aryloxy group, alkylthio group, arylthio group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, cyano group, sulfamoyl group, alkylsulfonyl group, arylsulfonyl group, and acyloxy group Can be mentioned.

The carbamoyl group represented by Q ₂ is preferably a carbamoyl group having 1 to 50 carbon atoms, more preferably 6 to 40 carbon atoms. For example, unsubstituted carbamoyl, methylcarbamoyl, N-ethylcarbamoyl, N-propylcarbamoyl N-sec-butylcarbamoyl, N-octylcarbamoyl, N-cyclohexylcarbamoyl, N-tert-butylcarbamoyl, N-dodecylcarbamoyl, N- (3-dodecyloxypropyl) carbamoyl, N-octadecylcarbamoyl, N- {3 -(2,4-tert-pentylphenoxy) propyl} carbamoyl, N- (2-hexyldecyl) carbamoyl, N-phenylcarbamoyl, N- (4-dodecyloxyphenyl) carbamoyl, N- (2-chloro-5 Dodecyloxycarbo Butylphenyl) carbamoyl, N- naphthylcarbamoyl, N-3- pyridylcarbamoyl, and N- benzylcarbamoyl.

The acyl group represented by Q ₂ is preferably an acyl group having 1 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as formyl, acetyl, 2-methylpropanoyl, cyclohexylcarbonyl, octanoyl, 2 -Hexyldecanoyl, dodecanoyl, chloroacetyl, trifluoroacetyl, benzoyl, 4-dodecyloxybenzoyl, 2-hydroxymethylbenzoyl. The alkoxycarbonyl group represented by Q ₂ is preferably an alkoxycarbonyl group having 2 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, isobutyloxycarbonyl, cyclohexyloxycarbonyl, Examples include dodecyloxycarbonyl and benzyloxycarbonyl.

The aryloxycarbonyl group represented by Q ₂ is preferably an aryloxycarbonyl group having 7 to 50 carbon atoms, more preferably 7 to 40 carbon atoms, such as phenoxycarbonyl, 4-octyloxyphenoxycarbonyl, 2-hydroxy Examples include methylphenoxycarbonyl and 4-dodecyloxyphenoxycarbonyl. The sulfonyl group represented by Q ₂ is preferably a sulfonyl group having 1 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as methylsulfonyl, butylsulfonyl, octylsulfonyl, 2-hexadecylsulfonyl, 3- Examples include dodecyloxypropylsulfonyl, 2-octyloxy-5-tert-octylphenylsulfonyl, and 4-dodecyloxyphenylsulfonyl.

The sulfamoyl group represented by Q ₂ is preferably a sulfamoyl group having 0 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as an unsubstituted sulfamoyl group, an N-ethylsulfamoyl group, N- (2- Ethylhexyl) sulfamoyl, N-decylsulfamoyl, N-hexadecylsulfamoyl, N- {3- (2-ethylhexyloxy) propyl} sulfamoyl, N- (2-chloro-5-dodecyloxycarbonylphenyl) sulfamoyl, And N- (2-tetradecyloxyphenyl) sulfamoyl. The group represented by Q ₂ may further have a group listed as an example of the substituent of the 5-membered to 7-membered unsaturated ring represented by Q ₁ at a substitutable position, When it has two or more substituents, these substituents may be the same or different.

Next, a preferable range of the compound represented by formula (A-1) is described. Q ₁ is preferably a 5- to 6-membered unsaturated ring, such as a benzene ring, pyrimidine ring, 1,2,3-triazole ring, 1,2,4-triazole ring, tetrazole ring, 1,3,4-thiadiazole ring. 1,2,4-thiadiazole ring, 1,3,4-oxadiazole ring, 1,2,4-oxadiazole ring, thiazole ring, oxazole ring, isothiazole ring, isoxazole ring, and these rings Is more preferably a ring fused with a benzene ring or an unsaturated heterocycle. Q ₂ is preferably a carbamoyl group, particularly preferably a carbamoyl group having a hydrogen atom on the nitrogen atom.

In General Formula (A-2), R ₁ represents an alkyl group, an acyl group, an acylamino group, a sulfonamide group, an alkoxycarbonyl group, or a carbamoyl group. R ₂ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acyloxy group, or a carbonate group. R ₃ and R ₄ each represents a group that can be substituted on the benzene ring mentioned in the example of the substituent of formula (A-1). R ₃ and R ₄ may be connected to each other to form a condensed ring.
R ₁ is preferably an alkyl group having 1 to 20 carbon atoms (for example, a methyl group, an ethyl group, an isopropyl group, a butyl group, a tert-octyl group, or a cyclohexyl group), an acylamino group (for example, an acetylamino group, a benzoylamino group, Methylureido group or 4-cyanophenylureido group), carbamoyl group (n-butylcarbamoyl group, N, N-diethylcarbamoyl group, phenylcarbamoyl group, 2-chlorophenylcarbamoyl group, 2,4-dichlorophenylcarbamoyl group, etc.) ) Is more preferably an acylamino group (including a ureido group and a urethane group). R ₂ is preferably a halogen atom (more preferably a chlorine atom or a bromine atom), an alkoxy group (such as a methoxy group, a butoxy group, an n-hexyloxy group, an n-decyloxy group, a cyclohexyloxy group, or a benzyloxy group), Or, it is an aryloxy group (phenoxy group, naphthoxy group, etc.).
R ₃ is preferably a hydrogen atom, a halogen atom, or an alkyl group having 1 to 20 carbon atoms, and most preferably a halogen atom. R ₄ is preferably a hydrogen atom, an alkyl group, or an acylamino group, and more preferably an alkyl group or an acylamino group. Examples of these preferable substituents are the same as those for R ₁ . When R ₄ is an acylamino group, R ₄ is preferably linked to R ₃ to form a carbostyryl ring.

In the general formula (A-2), when R ₃ and R ₄ are connected to each other to form a condensed ring, a naphthalene ring is particularly preferable as the condensed ring. The same substituent as the example of a substituent quoted by general formula (A-1) may couple | bond with the naphthalene ring. When general formula (A-2) is a naphthol-based compound, R ₁ is preferably a carbamoyl group. Of these, a benzoyl group is particularly preferable. R ₂ is preferably an alkoxy group or an aryloxy group, and particularly preferably an alkoxy group.

  Hereinafter, preferred specific examples of the development accelerator in the present invention will be given. The present invention is not limited to these.

(Description of hydrogen bonding compound)
When the reducing agent in the present invention has an aromatic hydroxyl group (—OH) or amino group (—NHR, R is a hydrogen atom or an alkyl group), particularly in the case of the bisphenols described above, these groups and hydrogen bonds It is preferable to use together a non-reducing compound having a group capable of forming.
Examples of the group that forms a hydrogen bond with a hydroxyl group or an amino group include a phosphoryl group, a sulfoxide group, a sulfonyl group, a carbonyl group, an amide group, an ester group, a urethane group, a ureido group, a tertiary amino group, and a nitrogen-containing aromatic group. Can be mentioned. Among them, preferred are a phosphoryl group, a sulfoxide group, an amide group (however, it has no> N—H group and is blocked like> N—Ra (Ra is a substituent other than H)), a urethane group. (However, it has no> N—H group and is blocked like> N—Ra (Ra is a substituent other than H)), a ureido group (however, it has no> N—H group,> N-Ra (Ra is a substituent other than H).)
In the present invention, a particularly preferred hydrogen bonding compound is a compound represented by the following general formula (D).

In the general formula (D), R ²¹ to R ²³ each independently represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group or a heterocyclic group, and these groups may be substituted even if they are unsubstituted. You may have.
When R ²¹ to R ²³ have a substituent, examples of the substituent include a halogen atom, an alkyl group, an aryl group, an alkoxy group, an amino group, an acyl group, an acylamino group, an alkylthio group, an arylthio group, a sulfonamide group, an acyloxy group, Examples thereof include an oxycarbonyl group, a carbamoyl group, a sulfamoyl group, a sulfonyl group, and a phosphoryl group, and a preferable substituent is an alkyl group or an aryl group such as a methyl group, an ethyl group, an isopropyl group, a t-butyl group, a t-butyl group. Examples include an octyl group, a phenyl group, a 4-alkoxyphenyl group, and a 4-acyloxyphenyl group.
Specific examples of the alkyl group of R ²¹ to R ²³ include a methyl group, an ethyl group, a butyl group, an octyl group, a dodecyl group, an isopropyl group, a t-butyl group, a t-amyl group, a t-octyl group, a cyclohexyl group, Examples include 1-methylcyclohexyl group, benzyl group, phenethyl group, and 2-phenoxypropyl group.
Examples of the aryl group include phenyl group, cresyl group, xylyl group, naphthyl group, 4-t-butylphenyl group, 4-t-octylphenyl group, 4-anisidyl group, and 3,5-dichlorophenyl group.
Alkoxy groups include methoxy, ethoxy, butoxy, octyloxy, 2-ethylhexyloxy, 3,5,5-trimethylhexyloxy, dodecyloxy, cyclohexyloxy, 4-methylcyclohexyloxy, and A benzyloxy group etc. are mentioned.
Examples of the aryloxy group include phenoxy group, cresyloxy group, isopropylphenoxy group, 4-t-butylphenoxy group, naphthoxy group, and biphenyloxy group.
Examples of the amino group include a dimethylamino group, a diethylamino group, a dibutylamino group, a dioctylamino group, an N-methyl-N-hexylamino group, a dicyclohexylamino group, a diphenylamino group, and an N-methyl-N-phenylamino group. It is done.

R ²¹ to R ²³ are preferably an alkyl group, an aryl group, an alkoxy group, or an aryloxy group. In view of the effects of the present invention, at least one of R ²¹ to R ²³ is preferably an alkyl group or an aryl group, and more preferably two or more are an alkyl group or an aryl group. In addition, it is preferable that R ²¹ to R ²³ are the same group in that they can be obtained at low cost.
Specific examples of the hydrogen bonding compound including the compound of the general formula (D) in the present invention are shown below, but the present invention is not limited thereto.

Specific examples of the hydrogen bonding compound include those described in European Patent No. 1096310, JP-A No. 2002-156727, and JP-A No. 2002-318431 in addition to the above.
The compound of the general formula (D) in the present invention can be used in a photothermographic material by being contained in a coating solution in the form of a solution, an emulsified dispersion, and a solid dispersed fine particle dispersion in the same manner as the reducing agent. It is preferably used as a solid dispersion. These compounds form a hydrogen-bonding complex with a compound having a phenolic hydroxyl group or amino group in a solution state, and depending on the combination of the reducing agent and the compound of the general formula (D) in the present invention, the compound may be crystallized as a complex It can be isolated in the state.
The use of the crystal powder isolated in this way as a solid dispersed fine particle dispersion is particularly preferable for obtaining stable performance. In addition, a method in which the reducing agent and the compound of the general formula (D) in the present invention are mixed in a powder form and complexed at the time of dispersion with a sand grinder mill or the like using an appropriate dispersant can be preferably used.
The compound of the general formula (D) in the present invention is preferably used in the range of 1 mol% to 200 mol%, more preferably in the range of 10 mol% to 150 mol%, based on the reducing agent. More preferably, it is the range of 20 mol% or more and 100 mol%.

(Description of silver halide)
1) Halogen composition The photosensitive silver halide used in the present invention is not particularly limited as a halogen composition, and is silver chloride, silver chlorobromide, silver bromide, silver iodobromide, silver iodochlorobromide, silver iodide. Can be used. Of these, silver bromide, silver iodobromide and silver iodide are preferred. The distribution of the halogen composition in the grains may be uniform, the halogen composition may be changed stepwise, or may be continuously changed. Further, silver halide grains having a core / shell structure can be preferably used. A preferable structure is a 2- to 5-fold structure, more preferably 2- to 4-fold core / shell particles. A technique for localizing silver bromide or silver iodide on the surface of silver chloride, silver bromide or silver chlorobromide grains can also be preferably used.

2) Grain Forming Methods Methods for forming photosensitive silver halide are well known in the art and are described, for example, in Research Disclosure No. 17029, June 1978, and US Pat. No. 3,700,458. In particular, a photosensitive silver halide is prepared by adding a silver supply compound and a halogen supply compound into gelatin or another polymer solution, and then mixed with an organic silver salt. Use the method. In addition, the method described in paragraph Nos. 0217 to 0224 of JP-A No. 11-119374, and the methods described in JP-A Nos. 11-352627 and 2000-347335 are also preferable.

3) Grain size The grain size of the photosensitive silver halide is preferably small for the purpose of reducing the cloudiness after image formation, specifically 0.20 μm or less, more preferably 0.01 μm or more and 0.15 μm or less. More preferably, it is 0.02 μm or more and 0.12 μm or less. The grain size here means the diameter when converted into a circular image having the same area as the projected area of silver halide grains (in the case of tabular grains, the projected area of the main plane).

4) Grain shape Examples of the shape of the silver halide grains include cubes, octahedrons, tabular grains, spherical grains, rod-like grains, and potato grains. In the present invention, cubic grains are particularly preferred. Grains with rounded corners of silver halide grains can also be preferably used. The surface index (Miller index) on the outer surface of the photosensitive silver halide grain is not particularly limited, but the ratio of the {100} plane, which has high spectral sensitizing efficiency when adsorbed by the spectral sensitizing dye, is high. preferable. The ratio is preferably 50% or more, more preferably 65% or more, and still more preferably 80% or more. The ratio of the Miller index {100} plane is a T.K. based on the adsorption dependency of {111} plane and {100} plane in the adsorption of a sensitizing dye. Tani; Imaging Sci. 29, 165 (1985).

5) Heavy Metal The photosensitive silver halide grain in the invention may contain a metal or metal complex of Group 6 to Group 13 of the Periodic Table (showing Groups 1 to 18). More preferably, a metal or metal complex of Group 6 to Group 10 can be contained. The metal of Group 6 to Group 10 of the periodic table or the central metal of the metal complex is preferably iron, rhodium, ruthenium, or iridium. One kind of these metal complexes may be used, or two or more kinds of complexes of the same metal and different metals may be used in combination. The preferred content is in the range of 1 × 10 ⁻⁹ mol to 1 × 10 ⁻³ mol with ^respect to 1 mol of silver. These heavy metals and metal complexes and methods for adding them are described in JP-A-7-225449, JP-A-11-65021, paragraphs 0018 to 0024, and JP-A-11-119374, paragraphs 0227 to 0240.

In the present invention, silver halide grains in which a hexacyano metal complex is present on the outermost surface of the grains are preferred. The hexacyano metal complexes include [Fe (CN) ₆ ] ⁴⁻ , [Fe (CN) ₆ ] ³⁻ , [Ru (CN) ₆ ] ⁴⁻ , [Os (CN) ₆ ] ⁴⁻ , [Co ( CN) ₆ ] ³⁻ , [Rh (CN) ₆ ] ³⁻ , [Ir (CN) ₆ ] ³⁻ , [Cr (CN) ₆ ] ³⁻ , [Re (CN) ₆ ] ^{3− and the} like. . In the present invention, a hexacyano Fe complex is preferred.

  The hexacyano metal complex is present in the form of ions in aqueous solution, so the counter cation is not important, but it is easy to mix with water and is suitable for precipitation of silver halide emulsions. Sodium ion, potassium ion, rubidium It is preferable to use alkali metal ions such as ions, cesium ions, and lithium ions, ammonium ions, and alkylammonium ions (for example, tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, or tetra (n-butyl) ammonium ion). .

  In addition to water, the hexacyano metal complex is miscible with a mixed solvent or gelatin with an appropriate organic solvent miscible with water (for example, alcohols, ethers, glycols, ketones, esters, amides, etc.). Can be added.

The addition amount of the hexacyano metal complex is preferably 1 × 10 ⁻⁵ mol or more and 1 × 10 ⁻² mol or less, more preferably 1 × 10 ⁻⁴ mol or more and 1 × 10 ⁻³ mol or less per mol of silver.

  In order for the hexacyano metal complex to be present on the outermost surface of the silver halide grain, the chalcogen sensitization of sulfur sensitization, selenium sensitization and tellurium sensitization is completed after the addition of the silver nitrate aqueous solution used for grain formation. It is added directly before the completion of the preparation step before the chemical sensitization step for performing noble metal sensitization such as sensitization and gold sensitization, during the washing step, during the dispersion step, or before the chemical sensitization step. In order to prevent the silver halide fine grains from growing, it is preferable to add the hexacyano metal complex immediately after the grain formation, and it is preferable to add it before the completion of the preparation step.

  The addition of the hexacyano metal complex may be started after adding 96% by mass of the total amount of silver nitrate to be added to form grains, more preferably starting after adding 98% by mass, The addition of 99% by mass is particularly preferable.

  When these hexacyanometal complexes are added after the addition of the aqueous silver nitrate solution just before the completion of grain formation, they can be adsorbed on the outermost surface of the silver halide grains, and most of them form slightly soluble salts with silver ions on the grain surface. To do. Since this silver salt of hexacyanoiron (II) is a less soluble salt than AgI, it is possible to prevent re-dissolution by fine particles and to produce silver halide fine particles having a small particle size. .

Furthermore, regarding the metal atoms (for example, [Fe (CN) ₆ ] ⁴⁻ ) that can be contained in the silver halide grains used in the present invention, the method of desalting silver halide emulsions and the method of chemical sensitization, JP-A-11-11 No. 84574, paragraph numbers 0046 to 0050, JP-A No. 11-65021, paragraph numbers 0025 to 0031, and JP-A No. 11-119374, paragraph numbers 0242 to 0250.

6) Gelatin As the gelatin contained in the photosensitive silver halide emulsion used in the present invention, various gelatins can be used. It is necessary to maintain the dispersion state of the photosensitive silver halide emulsion in the organic silver salt-containing coating solution, and gelatin having a molecular weight of 10,000 to 1,000,000 is preferably used. It is also preferable to phthalate the gelatin substituent. These gelatins may be used at the time of grain formation or at the time of dispersion after desalting, but are preferably used at the time of grain formation.

7) Sensitizing Dye Sensitizing dyes applicable to the present invention are those that can spectrally sensitize silver halide grains in a desired wavelength region when adsorbed on silver halide grains, and are suitable for the spectral characteristics of the exposure light source. Sensitizing dyes with sensitivity can be advantageously selected. Regarding the sensitizing dye and the addition method, paragraphs 0103 to 0109 of JP-A No. 11-65021, compounds represented by formula (II) of JP-A No. 10-186572, and formulas (I of JP-A No. 11-119374) ) And the dye described in Example 5 of U.S. Pat. Nos. 5,510,236 and 3,871,887, JP-A-2-96131, JP-A-59-48753. No. 19, page 38 to line 20, page 35 of European Patent Publication No. 0803764A1, JP 2001-272747, JP 2001-290238, JP 2002-23306, etc. It is described in. These sensitizing dyes may be used alone or in combination of two or more. In the present invention, the time when the sensitizing dye is added to the silver halide emulsion is preferably the time from the desalting step to the coating, and more preferably the time from desalting to the end of chemical ripening.
The addition amount of the sensitizing dye in the present invention can be set to a desired amount in accordance with the sensitivity and the fogging performance, but is preferably 10 ⁻⁶ mol to 1 mol per mol of silver halide in the image forming layer. The amount is preferably 10 ^-4 mol to 10 ^-1 mol.

  In the present invention, a supersensitizer can be used to improve spectral sensitization efficiency. As the supersensitizer used in the present invention, European Patent Publication No. 587,338, US Pat. Nos. 3,877,943, 4,873,184, JP-A-5-341432, 11- 109547, 10-111543, etc. are mentioned.

8) Chemical Sensitization The photosensitive silver halide grain in the invention is preferably chemically sensitized by sulfur sensitizing method, selenium sensitizing method or tellurium sensitizing method. As the compound preferably used in the sulfur sensitization method, selenium sensitization method, and tellurium sensitization method, known compounds such as compounds described in JP-A-7-128768 can be used. In the present invention, tellurium sensitization is particularly preferred. The compounds described in the literature described in paragraph No. 0030 of JP-A-11-65021, and the general formulas (II), (III), (IV) described in JP-A-5-313284 The compound shown by is more preferable.

  The photosensitive silver halide grains in the present invention are preferably chemically sensitized by gold sensitization alone or in combination with the chalcogen sensitization described above. As the gold sensitizer, the valence of gold is preferably +1 or +3, and the gold sensitizer is preferably a commonly used gold compound. Typical examples include chloroauric acid, bromoauric acid, potassium chloroaurate, potassium bromoaurate, auric trichloride, potassium auric thiocyanate, potassium iodoaurate, tetracyanoauric acid, ammonium aurothiocyanate, or pyridyltrichloro. Gold or the like is preferable. Further, gold sensitizers described in US Pat. No. 5,858,637 and JP-A No. 2002-278016 are also preferably used.

In the present invention, chemical sensitization can be performed at any time after particle formation and before coating. After desalting, (1) before spectral sensitization, (2) simultaneously with spectral sensitization, (3) spectral After sensitization, there may be (4) immediately before application.
The amount of sulfur, selenium and tellurium sensitizers used in the present invention varies depending on the silver halide grains used, chemical ripening conditions, etc., but is 10 ⁻⁸ mol or more and 10 ⁻² mol or less per mol of silver halide, Preferably, about 10 ⁻⁷ mol to 10 ⁻³ mol is used.
The amount of the gold sensitizer added varies depending on various conditions, but as a guideline, it is 10 ⁻⁷ mol or more and 10 ⁻³ mol or less, more preferably 10 ⁻⁶ mol or more and 5 × 10 ⁻⁴ mol or less per mol of silver halide. It is.
The conditions for chemical sensitization in the present invention are not particularly limited, but the pH is 5 to 8, the pAg is 6 to 11, and the temperature is about 40 ° C to 95 ° C.
A thiosulfonic acid compound may be added to the silver halide emulsion used in the present invention by the method described in European Patent Publication No. 293,917.

  A reducing agent is preferably used for the photosensitive silver halide grains in the present invention. As specific compounds of the reduction sensitization method, ascorbic acid and aminoiminomethanesulfinic acid are preferable. In addition, it is preferable to use stannous chloride, a hydrazine derivative, a borane compound, a silane compound, or a polyamine compound. The reduction sensitizer may be added at any stage in the photosensitive emulsion production process from crystal growth to the preparation process immediately before coating. Further, reduction sensitization is preferable by ripening while maintaining the pH of the emulsion at 7 or more or pAg at 8.3 or less, and reduction sensitization is achieved by introducing a single addition portion of silver ions during grain formation. It is also preferable to do.

9) Compound in which 1-electron oxidant produced by 1-electron oxidation can emit 1 electron or more electrons In the photothermographic material of the present invention, 1-electron oxidant produced by 1-electron oxidation is 1 electron or 1 electron or more. It is preferable to contain a compound capable of emitting more electrons. The compound can be used alone or in combination with the above-described various chemical sensitizers, and can increase the sensitivity of silver halide.

The one-electron oxidant produced by one-electron oxidation contained in the photothermographic material of the present invention is a compound selected from the following types 1 and 2 that can emit one or more electrons.
The type 1 and type 2 compounds contained in the silver halide photographic light-sensitive material of the present invention will be described.

(Type 1)
A compound in which a one-electron oxidant formed by one-electron oxidation can further emit one or more electrons with a subsequent bond cleavage reaction.
(Type 2)
A compound capable of emitting one or more electrons after a one-electron oxidant produced by one-electron oxidation undergoes a subsequent bond formation reaction.

First, the compound of type 1 will be described.
JP-A-9-211769 (specific examples: 28 to 15) is a compound that can emit one electron with a one-electron oxidant produced by one-electron oxidation of a type 1 compound, followed by a bond cleavage reaction. Compounds PMT-1 to S-37 described in Table E and Table F on page 32), JP-A-9-211774, JP-A-11-95355 (specific examples: compounds INV1 to 36), JP2001-500996 (Specific examples: Compounds 1-74, 80-87, 92-122), US Pat. No. 5,747,235, US Pat. No. 5,747,236, European Patent 786692A1 (Specific examples: Compounds INV 1-35), "One-photon two-electron sensitizer" or "deprotonated electron" described in patents such as European Patent No. 893732A1, US Pat. No. 6,054,260, US Pat. No. 5,994,051 Compound called Azukazo sensitizers "can be mentioned. The preferred ranges of these compounds are the same as the preferred ranges described in the cited patent specifications.

  Further, as a compound of type 1 that can be emitted by one-electron oxidant formed by one-electron oxidation and further undergoing bond cleavage reaction, one or more electrons can be emitted from the general formula (1) ( General formula (1) described in JP-A-2003-114487), general formula (2) (synonymous with general formula (2) described in JP-A-2003-114487), general formula (3) (JP-A-2003-114487) General formula (1) described in 2003-114488), general formula (4) (synonymous with general formula (2) described in Japanese Patent Application Laid-Open No. 2003-114488), and general formula (5) (Japanese Patent Application Laid-Open No. 2003-114488). 114488 (synonymous with general formula (3)), general formula (6) (synonymous with general formula (1) described in JP-A-2003-75950), and general formula (7) (JP-A-2003-75950). In the general formula (2)), the general formula (8) (Synonymous with the general formula (1) described in JP-A-2004-239934) or the reaction represented by the chemical reaction formula (1) (synonymous with the chemical reaction formula (1) described in JP-A-2004-245929) Among these compounds, compounds represented by the general formula (9) (synonymous with the general formula (3) described in JP-A No. 2004-245929) can be given. The preferred ranges of these compounds are the same as the preferred ranges described in the cited patent specifications.

In the general formulas (1) and (2), RED ₁ and RED ₂ represent a reducing group. R ₁ represents a non-metallic atomic group capable of forming a cyclic structure corresponding to a tetrahydro form of a 5-membered or 6-membered aromatic ring (including an aromatic heterocycle) or a hexahydro form together with carbon atom (C) and RED _1. To express. R ₂ , R ₃ and R ₄ represent a hydrogen atom or a substituent. Lv ₁ and Lv ₂ represent a leaving group. ED represents an electron donating group.

In the general formulas (3), (4) and (5), Z ₁ represents an atomic group capable of forming a 6-membered ring together with the nitrogen atom and the two carbon atoms of the benzene ring. _{R 5, R 6, R 7} , R 9, R 10, R 11, R 13, R 14, R 15, R 16, R 17, R 18, R 19 represents a hydrogen atom or a substituent. R ₂₀ represents a hydrogen atom or a substituent. When R ₂₀ represents a group other than an aryl group, R ₁₆ and R ₁₇ are bonded to each other to form an aromatic ring or an aromatic heterocycle. R ₈ and R ₁₂ represent a substituent that can be substituted on the benzene ring, m1 represents an integer of 0 to 3, and m2 represents an integer of 0 to 4. Lv ₃ , Lv ₄ and Lv ₅ represent a leaving group.

In the general formulas (6) and (7), RED ₃ and RED ₄ represent a reducing group. R _{21 to} R ₃₀ represent a hydrogen atom or a substituent. Z ₂ represents —CR ₁₁₁ R ₁₁₂ —, —NR ₁₁₃ —, or —O—. R ₁₁₁ and R ₁₁₂ each independently represents a hydrogen atom or a substituent. _R113 represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group.

In the general formula (8), RED ₅ is a reducing group and represents an arylamino group or a heterocyclic amino group. R ₃₁ represents a hydrogen atom or a substituent. X represents an alkoxy group, an aryloxy group, a heterocyclic oxy group, an alkylthio group, an arylthio group, a heterocyclic thio group, an alkylamino group, an arylamino group, or a heterocyclic amino group. Lv ₆ is a leaving group and represents a carboxy group or a salt thereof, or a hydrogen atom.

The compound represented by the general formula (9) is a compound that undergoes a bond formation reaction represented by the chemical reaction formula (1) by being further oxidized after two-electron oxidation accompanied by decarboxylation has occurred. In the chemical reaction formula (1), R ₃₂ and R ₃₃ represent a hydrogen atom or a substituent. Z ₃ represents a group which forms a 5-membered or 6-membered heterocycle with C═C. Z ₄ represents a group which forms a 5- or 6-membered aryl group or heterocyclic group with C═C. M represents a radical, a radical cation, or a cation. In the general formula (9), R ₃₂ , R ₃₃ and Z ₃ have the same meaning as in the chemical reaction formula (1). Z ₅ represents a group which forms a 5- or 6-membered cyclic aliphatic hydrocarbon group or heterocyclic group together with C—C.

Next, the type 2 compound will be described.
As a compound in which a one-electron oxidant produced by one-electron oxidation with a type 2 compound can further emit one or more electrons with a subsequent bond formation reaction, a compound represented by the general formula (10) A compound capable of causing a reaction represented by the general formula (1) described in 2003-140287) and the chemical reaction formula (1) (synonymous with the chemical reaction formula (1) described in JP-A-2004-245929). And a compound represented by the general formula (11) (synonymous with the general formula (2) described in JP-A No. 2004-245929). The preferred ranges of these compounds are the same as the preferred ranges described in the cited patent specifications.

General formula (10); RED ₆ -QY

In the general formula (10), RED ₆ represents a reducing group that is one-electron oxidized. Y reacts with a one-electron oxidant produced by one-electron oxidation of RED ₆ to form a new bond, a carbon-carbon double bond site, a carbon-carbon triple bond site, an aromatic group site, or Reactive group containing a non-aromatic heterocyclic moiety of a benzo-fused ring. Q represents a linking group linking RED ₆ and Y.

The compound represented by the general formula (11) is a compound that causes a bond formation reaction represented by the chemical reaction formula (1) by being oxidized. In the chemical reaction formula (1), R ₃₂ and R ₃₃ represent a hydrogen atom or a substituent. Z ₃ represents a group which forms a 5-membered or 6-membered heterocycle with C═C. Z ₄ represents a group which forms a 5- or 6-membered aryl group or heterocyclic group with C═C. Z ₅ represents a group which forms a 5- or 6-membered cyclic aliphatic hydrocarbon group or heterocyclic group together with C—C. M represents a radical, a radical cation, or a cation. In the general formula (11), R ₃₂ , R ₃₃ , Z ₃ and Z ₄ have the same meanings as those in the chemical reaction formula (1).

  Of the compounds of types 1 and 2, “a compound having an adsorptive group to silver halide in the molecule” or “a compound having a partial structure of a spectral sensitizing dye in the molecule” is preferable. Typical examples of the adsorptive group to silver halide are those described in JP-A No. 2003-156823, page 16, right line 1 to page 17, right line 12. The partial structure of the spectral sensitizing dye is a structure described on page 17, right line 34 to page 18, left line 6 of the same specification.

  More preferably, the compound of type 1 or 2 is “a compound having at least one adsorptive group to silver halide in the molecule”. More preferred is “a compound having two or more adsorptive groups to silver halide in the same molecule”. When two or more adsorptive groups are present in a single molecule, these adsorptive groups may be the same or different.

  The adsorptive group is preferably a mercapto-substituted nitrogen-containing heterocyclic group (for example, 2-mercaptothiadiazole group, 3-mercapto-1,2,4-triazole group, 5-mercaptotetrazole group, 2-mercapto-1,3,4). -Oxadiazole group, 2-mercaptobenzoxazole group, 2-mercaptobenzthiazole group, or 1,5-dimethyl-1,2,4-triazolium-3-thiolate group), or imino silver (> NAg) A nitrogen-containing heterocyclic group having a —NH— group that can be formed as a partial structure of a heterocyclic ring (for example, a benzotriazole group, a benzimidazole group, or an indazole group). Particularly preferred are 5-mercaptotetrazole group, 3-mercapto-1,2,4-triazole group, and benzotriazole group, most preferred are 3-mercapto-1,2,4-triazole group, and 5 -Mercaptotetrazole group.

  It is also particularly preferred that the adsorptive group has two or more mercapto groups as a partial structure in the molecule. Here, the mercapto group (—SH) may be a thione group if it can be tautomerized. Preferred examples of the adsorptive group having two or more mercapto groups as a partial structure (such as a dimercapto-substituted nitrogen-containing heterocyclic group) include 2,4-dimercaptopyrimidine group, 2,4-dimercaptotriazine group, 3, A 5-dimercapto-1,2,4-triazole group may be mentioned.

  A quaternary salt structure of nitrogen or phosphorus is also preferably used as the adsorptive group. Specific examples of the quaternary salt structure of nitrogen include an ammonio group (such as a trialkylammonio group, a dialkylaryl (or heteroaryl) ammonio group, an alkyldiaryl (or heteroaryl) ammonio group) or a quaternized nitrogen atom. A group containing a nitrogen-containing heterocyclic group containing As the quaternary salt structure of phosphorus, a phosphonio group (trialkylphosphonio group, dialkylaryl (or heteroaryl) phosphonio group, alkyldiaryl (or heteroaryl) phosphonio group, triaryl (or heteroaryl) phosphonio group, etc.) is used. Can be mentioned. More preferably, a quaternary salt structure of nitrogen is used, and more preferably a 5-membered or 6-membered nitrogen-containing aromatic heterocyclic group containing a quaternized nitrogen atom is used. Particularly preferably, a pyridinio group, a quinolinio group, or an isoquinolinio group is used. These nitrogen-containing heterocyclic groups containing a quaternized nitrogen atom may have an arbitrary substituent.

Examples of counter anions of quaternary salts include halogen ions, carboxylate ions, sulfonate ions, sulfate ions, perchlorate ions, carbonate ions, nitrate ions, BF ₄ ⁻ , PF ₆ ⁻ , Ph ₄ B ^{− and the} like. Can be mentioned. When a group having a negative charge in a carboxylate group or the like is present in the molecule, an inner salt may be formed together with the group. As a counter anion that is not present in the molecule, a chlorine ion, a bromo ion, or a methanesulfonate ion is particularly preferable.

  A preferred structure of the compound represented by type 1 or 2 having a quaternary salt structure of nitrogen or phosphorus as the adsorptive group is represented by the general formula (X).

Formula (X); (PQ ₁ −) _i −R (−Q ₂ −S) _j

In general formula (X), P and R each independently represent a quaternary salt structure of nitrogen or phosphorus that is not a partial structure of a sensitizing dye. Q ₁ and Q ₂ each independently represent a linking group, specifically a single bond, an alkylene group, an arylene group, a heterocyclic group, —O—, —S—, —NR _N —, —C (═O ) —, —SO ₂ —, —SO—, —P (═O) — each independently or a combination of these groups. Here, _RN represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. S is a residue obtained by removing one atom from a compound represented by type (1) or (2). i and j are integers of 1 or more, and i + j is selected from the range of 2-6. Preferably, i is 1 to 3, and j is 1 to 2, more preferably i is 1 or 2, and j is 1, and particularly preferably i is 1 and j is 1. The compound represented by the general formula (X) preferably has a total carbon number of 10 to 100. More preferably, it is 10-70, More preferably, it is 11-60, Most preferably, it is 12-50.

  Specific examples of the compounds represented by type 1 and type 2 are listed below, but the present invention is not limited thereto.

  The compounds of type 1 and type 2 in the present invention may be used at any time during the preparation of the emulsion and during the light-sensitive material production process. For example, at the time of particle formation, desalting step, chemical sensitization, and before coating. Moreover, it can also add in several steps in these processes. The addition position is preferably from the end of particle formation to before the desalting step, at the time of chemical sensitization (from immediately before the start of chemical sensitization to immediately after the end), and before application, more preferably at the time of chemical sensitization and before application.

  The compounds of type 1 and type 2 in the present invention are preferably added after being dissolved in water, a water-soluble solvent such as methanol or ethanol, or a mixed solvent thereof. When the compound is dissolved in water, the compound having higher solubility when the pH is increased or decreased may be dissolved at a higher or lower pH and added.

The compounds of type 1 and type 2 in the present invention are preferably used in the emulsion layer (image forming layer), but may be added to the protective layer or intermediate layer together with the image forming layer and diffused during coating. The timing of addition of the compound of the present invention is preferably 1 × 10 ⁻⁹ mol or more and 5 × 10 ⁻² mol or less, more preferably 1 × 10 ⁻⁸ mol per mol of silver halide, regardless of before and after the sensitizing dye. It is contained in the silver halide emulsion layer (image forming layer) at a ratio of not less than 2 mol and not more than 2 × 10 ⁻³ mol.

10) Adsorbing redox compound having an adsorbing group and a reducing group In the present invention, it is preferable to contain an adsorbing redox compound having an adsorbing group and a reducing group for silver halide in the molecule. The adsorptive redox compound is preferably a compound represented by the following formula (I).

Formula (I): A- (W) n-B
In the formula (I), A represents a group capable of adsorbing to silver halide (hereinafter referred to as an adsorbing group), W represents a divalent linking group, n represents 0 or 1, and B represents a reducing group. To express.

  In the formula (I), the adsorption group represented by A is a group that directly adsorbs to silver halide, or a group that promotes adsorption to silver halide, and specifically, a mercapto group (or a salt thereof). , A thione group (—C (═S) —), a heterocyclic group, a sulfide group, a disulfide group, a cationic group, or an ethynyl group containing at least one atom selected from a nitrogen atom, a sulfur atom, a selenium atom, and a tellurium atom Etc.

The mercapto group (or salt thereof) as the adsorptive group means the mercapto group (or salt thereof) itself, and more preferably a heterocyclic group or aryl group substituted with at least one mercapto group (or salt thereof) or Represents an alkyl group. Here, the heterocyclic group is at least a 5- to 7-membered monocyclic or condensed aromatic or non-aromatic heterocyclic group such as an imidazole ring group, a thiazole ring group, an oxazole ring group, or a benzimidazole ring. Group, benzothiazole ring group, benzoxazole ring group, triazole ring group, thiadiazole ring group, oxadiazole ring group, tetrazole ring group, purine ring group, pyridine ring group, quinoline ring group, isoquinoline ring group, pyrimidine ring group, And triazine ring group. Moreover, the heterocyclic group containing the quaternized nitrogen atom may be sufficient, and in this case, the substituted mercapto group may dissociate and it may become a meso ion. When the mercapto group forms a salt, the counter ion includes a cation such as alkali metal, alkaline earth metal, heavy metal (Li ⁺ , Na ⁺ , K ⁺ , Mg ²⁺ , Ag ⁺ , Zn ^2+, etc.), ammonium ion Examples thereof include a heterocyclic group containing a quaternized nitrogen atom, and a phosphonium ion.
Further, the mercapto group as the adsorptive group may be tautomerized into a thione group.
The thione group as an adsorbing group also includes a chain or cyclic thioamide group, thioureido group, thiourethane group, or dithiocarbamate group.
A heterocyclic group containing at least one atom selected from a nitrogen atom, a sulfur atom, a selenium atom and a tellurium atom as the adsorptive group is a -NH- group capable of forming imino silver (> NAg) as a partial structure of the heterocyclic ring. A nitrogen-containing heterocyclic group, or a heterocyclic ring having a -S- group, a -Se- group, a -Te- group, or a = N- group as a partial structure of the heterocyclic ring, which can be coordinated to a silver ion by a coordination bond Examples of the former include benzotriazole group, triazole group, indazole group, pyrazole group, tetrazole group, benzimidazole group, imidazole group, and purine group, and examples of the latter include thiophene group, thiazole group, and oxazole group. , Benzothiophene group, benzothiazole group, benzoxazole group, thiadiazole group, oxadiazole group, triazine group, Azole group, benzoselenazole group, tellurium azole group, and the like benzo tellurium azole group.
Examples of the sulfide group or disulfide group as the adsorptive group include all groups having a partial structure of -S- or -SS-.
The cationic group as the adsorptive group means a group containing a quaternized nitrogen atom, specifically, an ammonio group or a group containing a nitrogen-containing heterocyclic group containing a quaternized nitrogen atom. Examples of the nitrogen-containing heterocyclic group containing a quaternized nitrogen atom include a pyridinio group, a quinolinio group, an isoquinolinio group, and an imidazolio group.
An ethynyl group as an adsorbing group means a —C≡CH group, and the hydrogen atom may be substituted.
The adsorbing group may have an arbitrary substituent.

  Further, specific examples of the adsorbing group include those described in the specifications p4 to p7 of JP-A No. 11-95355.

  In the formula (I), preferred as the adsorptive group represented by A is a mercapto-substituted heterocyclic group (for example, 2-mercaptothiadiazole group, 2-mercapto-5-aminothiadiazole group, 3-mercapto-1,2,4). -Triazole group, 5-mercaptotetrazole group, 2-mercapto-1,3,4-oxadiazole group, 2-mercaptobenzimidazole group, 1,5-dimethyl-1,2,4-triazolium-3-thiolate group 2,4-dimercaptopyrimidine group, 2,4-dimercaptotriazine group, 3,5-dimercapto-1,2,4-triazole group, or 2,5-dimercapto-1,3-thiazole group), Alternatively, a nitrogen-containing heterocyclic group having a —NH— group that can form imino silver (> NAg) as a partial structure of the heterocyclic ring (for example, benzotri A tetrazole group, a benzimidazole group, an indazole group, or the like), more preferable as an adsorptive group is a 2-mercaptobenzimidazole group, a 3,5-dimercapto-1,2,4-triazole group.

In formula (I), W represents a divalent linking group. Any linking group may be used as long as it does not adversely affect photographic properties. For example, a divalent linking group composed of a carbon atom, a hydrogen atom, an oxygen atom, a nitrogen atom, or a sulfur atom can be used. Specifically, an alkylene group having 1 to 20 carbon atoms (for example, a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a hexamethylene group, etc.), an alkenylene group having 2 to 20 carbon atoms, and an alkynylene group having 2 to 20 carbon atoms. , Arylene groups having 6 to 20 carbon atoms (eg, phenylene group, naphthylene group, etc.), —CO—, —SO ₂ —, —O—, —S—, —NR ₁ —, combinations of these linking groups, and the like. It is done. Here, R ₁ represents a hydrogen atom, an alkyl group, a heterocyclic group, or an aryl group.
The linking group represented by W may have an arbitrary substituent.

  In formula (I), the reducing group represented by B represents a group capable of reducing silver ions. For example, a triple bond group such as formyl group, amino group, acetylene group or propargyl group, mercapto group, hydroxylamines. Hydroxamic acids, hydroxyureas, hydroxyurethanes, hydroxysemicarbazides, reductones (including reductone derivatives), anilines, phenols (chroman-6-ols, 2,3-dihydrobenzofuran-5-ols, Aminophenols, sulfonamidophenols, and hydroquinones, catechols, resorcinols, polyphenols such as benzenetriols, or bisphenols), acylhydrazines, carbamoylhydrazines, or 3-pyrazolidones Remove one hydrogen atom Residues, and the like. Of course, these may have an arbitrary substituent.

In the formula (I), the reducing group represented by B shows its oxidation potential by Akira Fujishima “Electrochemical measurement method” (pages 150-208, published by Gihodo) or “The Experimental Chemistry Course” edited by the Chemical Society of Japan, 4th edition ( 9 pages 282-344, Maruzen). For example, by a rotating disk voltammetry technique, specifically, a sample is dissolved in a solution of methanol: pH 6.5 Briton-Robinson buffer = 10%: 90% (volume%), and nitrogen gas is used for 10 minutes. , A glassy carbon rotating disk electrode (RDE) is used as a working electrode, a platinum wire is used as a counter electrode, a saturated calomel electrode is used as a reference electrode, 25 ° C., 1000 rev / min, 20 mV / sec. Can be measured at sweep speed. A half-wave potential (E1 / 2) can be obtained from the obtained voltammogram.
In the present invention, the reducing group represented by B preferably has an oxidation potential in the range of about −0.3 V to about 1.0 V when measured by the above measurement method. More preferably, it is in the range of about -0.1V to about 0.8V, and particularly preferably in the range of about 0 to about 0.7V.

  In the formula (I), the reducing group represented by B is preferably hydroxylamines, hydroxamic acids, hydroxyureas, hydroxysemicarbazides, reductones, phenols, acylhydrazines, carbamoylhydrazines, or 3-pyrazolidones. Is a residue obtained by removing one hydrogen atom from

  The compound of the formula (I) in the present invention may be one in which a ballast group or polymer chain commonly used in an immobile photographic additive such as a coupler is incorporated. Examples of the polymer include those described in JP-A-1-100530.

  The compound of the formula (I) in the present invention may be a bis form or a tris form. The molecular weight of the compound of formula (I) in the present invention is preferably between 100 and 10000, more preferably between 120 and 1000, particularly preferably between 150 and 500.

  Examples of the compound of formula (I) in the present invention are shown below, but the present invention is not limited thereto.

  Furthermore, specific compounds 1 to 30 and 1 ″ -1 to 1 ″ -77 described in European Patent No. 1308776A2 p73 to p87 are also preferable examples of the compound having an adsorbing group and a reducing group in the present invention.

  These compounds can be easily synthesized according to known methods. As the compound of the formula (I) in the present invention, one kind of compound may be used alone, but it is also preferred to use two or more kinds of compounds at the same time. When two or more kinds of compounds are used, they may be added in the same layer or in different layers, and the addition method may be different.

The compound of formula (I) in the present invention is preferably added to the silver halide emulsion layer (image forming layer), and more preferably added during the preparation of the emulsion. When added at the time of emulsion preparation, it can be added at any time during the process. For example, silver halide grain formation process, before the start of desalting process, desalting process, chemical ripening Examples include a step before starting, a chemical ripening step, and a step before preparing a finished emulsion. Moreover, it can also be added in several steps in these processes. Although it is preferably used for the image forming layer, it may be added to the adjacent protective layer or intermediate layer together with the image forming layer and diffused during coating.
The preferred addition amount largely depends on the above-mentioned addition method and the kind of the compound to be added, but generally 1 × 10 ⁻⁶ mol to 1 mol, preferably 1 × 10 ⁻⁵ mol per mol of photosensitive silver halide. The amount is 5 × 10 ⁻¹ mol or less, more preferably 1 × 10 ⁻⁴ mol or more and 1 × 10 ⁻¹ mol or less.

  The compound of the formula (I) in the present invention can be added after being dissolved in water, a water-soluble solvent such as methanol or ethanol, or a mixed solvent thereof. At this time, the pH may be appropriately adjusted with an acid or a base, and a surfactant may be allowed to coexist. Furthermore, it can also be dissolved in a high boiling point organic solvent and added as an emulsified dispersion. It can also be added as a solid dispersion.

11) Two or more silver halides used in combination The photosensitive silver halide emulsion in the photothermographic material used in the invention may be only one type, or two or more types (for example, those having different average grain sizes or different halogen compositions). Those having different crystal habits, those having different chemical sensitization conditions) may be used in combination. The gradation can be adjusted by using a plurality of photosensitive silver halides having different sensitivities. Examples of these technologies include JP-A-57-119341, JP-A-53-106125, JP-A-47-3929, JP-A-48-55730, JP-A-46-5187, JP-A-50-73627, and JP-A-57-150841. Can be mentioned. The sensitivity difference is preferably 0.2 log E or more for each emulsion.

12) Application amount The addition amount of photosensitive silver halide is preferably 0.03 g / m ² or more and 0.6 g / m ² or less, expressed as the amount of silver applied per 1 m ² of the light-sensitive material. / M ² or more and 0.4 g / m ² or less is more preferable, and 0.07 g / m ² or more and 0.3 g / m ² or less is most preferable. The functional silver halide is preferably from 0.01 mol to 0.5 mol, more preferably from 0.02 mol to 0.3 mol, and still more preferably from 0.03 mol to 0.2 mol.

13) Mixing of photosensitive silver halide and organic silver salt Regarding the mixing method and mixing conditions of separately prepared photosensitive silver halide and organic silver salt, the silver halide grains and the organic silver salt that were prepared are respectively stirred at high speed. Prepare an organic silver salt by mixing with a machine, ball mill, sand mill, colloid mill, vibration mill, homogenizer, etc., or mixing photosensitive silver halide that has been prepared at any time during the preparation of the organic silver salt However, there is no particular limitation as long as the effects of the present invention are sufficiently exhibited. In addition, mixing two or more organic silver salt aqueous dispersions and two or more photosensitive silver salt aqueous dispersions when mixing is a preferred method for adjusting photographic characteristics.

14) Mixing of silver halide into coating solution The preferred addition time of silver halide to the image forming layer coating solution is from 180 minutes before application, preferably from 60 minutes to 10 seconds before application. The method and mixing conditions are not particularly limited as long as the effects of the present invention are sufficiently exhibited. Specific mixing methods include mixing in a tank in which the average residence time calculated from the addition flow rate and the amount of liquid fed to the coater is a desired time. Harnby, M.M. F. Edwards, A.D. W. There is a method of using a static mixer described in Chapter 8 of Nienow's Koji Takahashi's “Liquid mixing technology” (published by Nikkan Kogyo Shimbun, 1989).

(Description of binder)
As the binder for the image forming layer in the present invention, any polymer may be used. Suitable binders are transparent or translucent and generally colorless, and are natural resins, polymers and copolymers, synthetic resins, polymers and copolymers, and other films. Forming media such as gelatins, rubbers, poly (vinyl alcohol) s, hydroxyethyl celluloses, cellulose acetates, cellulose acetate butyrates, poly (vinyl pyrrolidone) s, casein, starch, poly (acrylic acid) , Poly (methyl methacrylic acid) s, poly (vinyl chloride) s, poly (methacrylic acid) s, styrene-maleic anhydride copolymers, styrene-acrylonitrile copolymers, styrene-butadiene copolymers, Poly (vinyl acetal) s (for example, poly (vinyl acetal) (Formal) and poly (vinyl butyral)), poly (esters), poly (urethane) s, phenoxy resins, poly (vinylidene chloride) s, poly (epoxides), poly (carbonates), poly (vinyl acetate) s , Poly (olefin) s, cellulose esters, or poly (amides). The binder may be formed from water, an organic solvent or an emulsion.

  In the present invention, the glass transition temperature of the binder that can be used in combination with the layer containing the organic silver salt is preferably 0 ° C. or higher and 80 ° C. or lower (hereinafter sometimes referred to as a high Tg binder), and preferably 10 ° C. to 70 ° C. Is more preferable, and it is still more preferable that it is 15 to 60 degreeC.

In this specification, Tg was calculated by the following formula.
1 / Tg = Σ (Xi / Tgi)
Here, it is assumed that n monomer components from i = 1 to n are copolymerized in the polymer. Xi is the mass fraction of the i-th monomer (ΣXi = 1), and Tgi is the glass transition temperature (absolute temperature) of the homopolymer of the i-th monomer. However, Σ is the sum from i = 1 to n. In addition, the value (Tgi) of the homopolymer glass transition temperature of each monomer employ | adopted the value of Polymer Handbook (3rd Edition) (J. Brandrup, EH Immergut (Wiley-Interscience, 1989)).

  Two or more binders may be used in combination as required. Further, a glass transition temperature of 20 ° C. or higher and a glass transition temperature of less than 20 ° C. may be used in combination. When two or more types of polymers having different Tg are blended, the mass average Tg is preferably within the above range.

In the present invention, it is preferable that the image forming layer is coated and dried using a coating solution in which 30% by mass or more of the solvent is water to form a film.
In the present invention, when the image forming layer is formed using a coating solution in which 30% by mass or more of the solvent is water and dried, the binder of the image forming layer is further added to an aqueous solvent (aqueous solvent). When it is soluble or dispersible, the performance is improved particularly when it is made of a latex of a polymer having an equilibrium water content of 2% by mass or less at 25 ° C. and 60% RH. The most preferable form is one prepared so that the ionic conductivity is 2.5 mS / cm or less, and as such a preparation method, there is a method of purifying using a separation functional membrane after polymer synthesis.

  The aqueous solvent in which the polymer is soluble or dispersible here is a mixture of water or water and 70% by mass or less of a water-miscible organic solvent. Examples of the water-miscible organic solvent include alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol, cellosolvs such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve, ethyl acetate, and dimethylformamide.

  In the case of a system in which the polymer is not dissolved thermodynamically and exists in a so-called dispersed state, the term aqueous solvent is used here.

The “equilibrium moisture content at 25 ° C. and 60% RH” is the following using the mass W1 of the polymer in a humidity-controlled equilibrium under an atmosphere of 25 ° C. and 60% RH and the mass W0 of the polymer in an absolutely dry state at 25 ° C. It can be expressed as
Equilibrium moisture content at 25 ° C. and 60% RH = {(W1−W0) / W0} × 100 (mass%)

  For the definition and measurement method of moisture content, for example, Polymer Engineering Course 14, Polymer Material Testing Method (Edited by Society of Polymer Sciences, Jinshokan) can be referred to.

  The equilibrium water content at 25 ° C. and 60% RH of the binder polymer in the present invention is preferably 2% by mass or less, more preferably 0.01% by mass or more and 1.5% by mass or less, and still more preferably 0.02%. Desirably, the content is from 1% by mass to 1% by mass.

  In the present invention, a polymer dispersible in an aqueous solvent is particularly preferred. Examples of the dispersed state may be either latex in which fine particles of water-insoluble hydrophobic polymer are dispersed or polymer molecules dispersed in a molecular state or forming micelles. preferable. The average particle size of the dispersed particles is 1 nm or more and 50000 nm or less, preferably 5 nm or more and 1000 nm or less, more preferably 10 nm or more and 500 nm or less, and further preferably 50 nm or more and 200 nm or less. The particle size distribution of the dispersed particles is not particularly limited, and may have a wide particle size distribution or a monodispersed particle size distribution. Mixing two or more types having a monodispersed particle size distribution is also a preferable method for controlling the physical properties of the coating solution.

  In the present invention, preferred embodiments of the polymer that can be dispersed in an aqueous solvent include acrylic polymers, poly (esters), rubbers (eg, SBR resin), poly (urethanes), poly (vinyl chloride) s, poly (acetic acid). Hydrophobic polymers such as vinyl), poly (vinylidene chloride), or poly (olefin) can be preferably used. These polymers may be linear polymers, branched polymers, crosslinked polymers, so-called homopolymers obtained by polymerizing a single monomer, or copolymers obtained by polymerizing two or more types of monomers. In the case of a copolymer, it may be a random copolymer or a block copolymer. The molecular weight of these polymers is 5,000 to 1,000,000, preferably 10,000 to 200,000 in terms of number average molecular weight. When the molecular weight is too small, the mechanical strength of the image forming layer is insufficient, and when the molecular weight is too large, the film formability is poor, which is not preferable. A crosslinkable polymer latex is particularly preferably used.

(Specific examples of latex)
Specific examples of preferable polymer latex include the following. Below, it represents using a raw material monomer, the numerical value in a parenthesis is the mass%, and molecular weight is a number average molecular weight.
When a polyfunctional monomer was used, the concept of molecular weight was not applicable because a crosslinked structure was formed, so it was described as crosslinkability, and the description of molecular weight was omitted. Tg represents the glass transition temperature.

NP-1; -MMA (70) -EA (27) -MAA (3)-latex (molecular weight 37000, Tg 61 ° C.)
NP-2; latex of -MMA (70) -2EHA (20) -St (5) -AA (5)-(molecular weight 40000, Tg 59 ° C.)
-NP-3; latex of -St (50) -Bu (47) -MAA (3)-(crosslinkability, Tg-17 ° C)
-NP-4; -St (68) -Bu (29) -AA (3)-latex (crosslinkable, Tg 17 ° C)
NP-5; Latex of -St (71) -Bu (26) -AA (3)-(crosslinkability, Tg 24 ° C.)
NP-6; Latex (crosslinkable) of -St (70) -Bu (27) -IA (3)-
NP-7; latex of -St (75) -Bu (24) -AA (1)-(crosslinkability, Tg 29 ° C.)
NP-8; Latex (crosslinkable) of -St (60) -Bu (35) -DVB (3) -MAA (2)-
NP-9; Latex (crosslinkable) of -St (70) -Bu (25) -DVB (2) -AA (3)-
NP-10; latex of VC (50) -MMA (20) -EA (20) -AN (5) -AA (5)-(molecular weight 80,000)
-NP-11; -VDC (85) -MMA (5) -EA (5) -MAA (5)-latex (molecular weight 67000)
NP-12; -Et (90) -MAA (10)-latex (molecular weight 12000)
NP-13; -St (70) -2EHA (27) -AA (3) latex (molecular weight 130,000, Tg 43 ° C.)
NP-14; latex of MMA (63) -EA (35) -AA (2) (molecular weight 33000, Tg 47 ° C.)
-NP-15; -St (70.5) -Bu (26.5) -AA (3) -latex (crosslinkability, Tg 23 ° C.)
NP-16; latex of -St (69.5) -Bu (27.5) -AA (3)-(crosslinkability, Tg 20.5 ° C)
-NP-17; latex of -St (61.3) -isoprene (35.5) -AA (3)-(crosslinkability, Tg17 ° C)
NP-18; latex of -St (67) -isoprene (28) -Bu (2) -AA (3)-(crosslinkability, Tg 27 ° C.)

  The abbreviations for the above structures represent the following monomers. MMA; Methyl methacrylate, EA; Ethyl acrylate, MAA; Methacrylic acid, 2EHA; 2-Ethylhexyl acrylate, St; Styrene, Bu; Butadiene, AA; Acrylic acid, DVB; Divinylbenzene, VC; Vinyl chloride, AN; Acrylonitrile, VDC Vinylidene chloride, Et; ethylene, IA; itaconic acid.

  The polymer latex described above is also commercially available, and the following polymers can be used. Examples of the acrylic polymer include Sebian A-4635, 4718, 4601 (manufactured by Daicel Chemical Industries, Ltd.), Nipol Lx811, 814, 821, 820, 857 (manufactured by Nippon Zeon Co., Ltd.), etc. Examples of poly (esters) include poly (urethane) such as FINETEX ES650, 611, 675, 850 (above, manufactured by Dainippon Ink Chemical Co., Ltd.), WD-size, WMS (above, manufactured by Eastman Chemical). Examples of rubbers include HYDRAN AP10, 20, 30, 40 (manufactured by Dainippon Ink Chemical Co., Ltd.), and examples of rubbers include LACSTAR 7310K, 3307B, 4700H, 7132C (above, Dainippon Ink Chemical Co., Ltd.). (Made by Co., Ltd.), Nipol Lx416, 410, 438C, 2507 (above, Nippon Zeo) As examples of poly (vinyl chloride) such as G351 and G576 (above, manufactured by Nippon Zeon Co., Ltd.), examples of poly (vinylidene chloride) such as L502, L513 (above Examples of poly (olefin) s such as Asahi Kasei Kogyo Co., Ltd. include Chemipearl S120 and SA100 (above Mitsui Petrochemical Co., Ltd.).

  These polymer latexes may be used alone or in combination of two or more as required.

(Preferred latex)
As the polymer latex used in the present invention, styrene-butadiene copolymer or styrene-isoprene copolymer latex is particularly preferable. The mass ratio of the styrene monomer unit to the butadiene monomer unit in the styrene-butadiene copolymer is preferably 40:60 to 95: 5. The proportion of the styrene monomer unit and the butadiene monomer unit in the copolymer is preferably 60% by mass to 99% by mass. Moreover, it is preferable that the polymer latex in this invention contains acrylic acid or methacrylic acid 1 mass%-6 mass% with respect to the sum of styrene and butadiene, More preferably, it contains 2 mass%-5 mass%. The polymer latex in the present invention preferably contains acrylic acid. The preferable range of the monomer content is the same as described above. The preferred copolymer ratio and acrylic acid content in the styrene-isoprene copolymer are the same as in the styrene-butadiene copolymer.

  Examples of latexes of styrene-butadiene acid copolymer that are preferably used in the present invention include the aforementioned P-3 to P-9,15, commercially available products LACSTAR-3307B, 7132C, Nipol Lx416, and the like. Examples of the styrene-isoprene copolymer include the aforementioned P-16 and 17.

  If necessary, a hydrophilic polymer such as gelatin, polyvinyl alcohol, methyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose may be added to the image forming layer of the photothermographic material of the invention. The amount of these hydrophilic polymers added is preferably 30% by mass or less, more preferably 20% by mass or less, based on the total binder of the image forming layer.

  The organic silver salt-containing layer (that is, the image forming layer) in the present invention is preferably formed using a polymer latex. The amount of binder in the image forming layer is such that the total binder / organic silver salt mass ratio is 1/10 to 10/1, more preferably 1/3 to 5/1, and still more preferably 1/1 to 3/1. Range.

  Further, such an organic silver salt-containing layer is usually a photosensitive layer (image forming layer) containing a photosensitive silver halide that is a photosensitive silver salt. The mass ratio of silver halide is 400-5, more preferably 200-10.

The total binder amount of the image forming layer in the present invention is preferably 0.2 g / m ² or more and 30 g / m ² or less, more preferably 1 g / m ² or more and 15 g / m ² or less, and further preferably 2 g / m ² or more and 10 g. / M ² or less. In the image forming layer of the present invention, a crosslinking agent for crosslinking, a surfactant for improving coating properties, and the like may be added.

(Preferable solvent for coating solution)
In the present invention, the solvent of the image forming layer coating solution of the photothermographic material (here, for simplicity, the solvent and the dispersion medium are collectively referred to as a solvent) is preferably an aqueous solvent containing 30% by mass or more of water. As a component other than water, any water-miscible organic solvent such as methyl alcohol, ethyl alcohol, isopropyl alcohol, methyl cellosolve, ethyl cellosolve, dimethylformamide, and ethyl acetate may be used. The water content of the solvent of the coating solution is preferably 50% by mass or more, more preferably 70% by mass or more. Examples of preferred solvent compositions include water, water / methyl alcohol = 90/10, water / methyl alcohol = 70/30, water / methyl alcohol / dimethylformamide = 80/15/5, water / methyl alcohol / Ethyl cellosolve = 85/10/5, water / methyl alcohol / isopropyl alcohol = 85/10/5, etc. (numerical values are mass%).

(Description of thermal solvent)
In the present invention, the photothermographic material can contain a thermal solvent. Here, the thermal solvent is defined as a material capable of lowering the thermal development temperature by 1 ° C. or more compared to the thermal development photosensitive material containing no thermal solvent with respect to the thermal solvent-containing thermal development photosensitive material. More preferred are materials that can lower the heat development temperature by 2 ° C. or more, and particularly preferred are materials that can be lowered by 3 ° C. or more. For example, with respect to the photothermographic material A containing a thermal solvent, when the photothermographic material containing no thermal solvent from the photothermographic material A is B, the photothermographic material B is exposed to a thermal development temperature of 120 ° C. A thermal solvent is used when the heat development temperature is 119 ° C. or less to obtain the density obtained by processing with a heat development time of 20 seconds with the same exposure amount and heat development time for the photothermographic material A.

  By adding a thermal solvent, the development speed is improved, so that the apparent sensitivity can be improved, but it is easily affected by the external environment (storage state, etc.). However, the layer structure of the present invention makes it difficult to be influenced by the external environment.

  The thermal solvent of the present invention has a polar group as a substituent and is preferably represented by the formula (1), but is not limited thereto.

      Formula (1) (Y) nZ

In the formula (1), Y represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group. Z represents a group selected from a hydroxy group, carboxy group, amino group, amide group, sulfonamide group, phosphoric acid amide group, cyano group, imide, ureido, sulfoxide, sulfone, phosphine, phosphine oxide or nitrogen-containing heterocyclic group. . n represents an integer of 1 to 3, which is 1 when Z is a monovalent group, and is the same as the valence of Z when Z is a divalent or higher group. When n is 2 or more, the plurality of Y may be the same or different.
Y may further have a substituent, and may have a group represented by Z as a substituent.

Y will be described in more detail. In the formula (1), Y is a linear, branched or cyclic alkyl group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 25 carbon atoms such as methyl, ethyl, n- Propyl, iso-propyl, sec-butyl, t-butyl, t-octyl, n-amyl, t-amyl, n-dodecyl, n-tridecyl, octadecyl, icosyl, docosyl, cyclopentyl, cyclohexyl, etc.). An alkenyl group (preferably having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 25 carbon atoms such as vinyl, allyl, 2-butenyl, and 3-pentenyl), an aryl group (Preferably has 6 to 40 carbon atoms, more preferably 6 to 30 carbon atoms, particularly preferably 6 to 25 carbon atoms. Ruphenyl, naphthyl, etc.), heterocyclic groups (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms such as pyridyl, pyrazyl, imidazolyl, pyrrolidyl, etc. It is mentioned.) These substituents may be further substituted with other substituents. These substituents may be bonded to each other to form a ring.
Y may further have a substituent. Examples of the substituent include a halogen atom (a fluorine atom, a chloro atom, a bromine atom, or an iodine atom), an alkyl group (a linear, branched, or cyclic alkyl group). , Bicycloalkyl groups and active methine groups), alkenyl groups, alkynyl groups, aryl groups, heterocyclic groups (regardless of the position of substitution), acyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, heterocyclic oxycarbonyl groups Carbamoyl group, N-acylcarbamoyl group, N-sulfonylcarbamoyl group, N-carbamoylcarbamoyl group, thiocarbamoyl group, N-sulfamoylcarbamoyl group, carbazoyl group, carboxy group or a salt thereof, oxalyl group, oxamoyl group, cyano Group, carbonimidoyl group (Carbonimide group) , Formyl group, hydroxy group, alkoxy group (including groups containing ethyleneoxy group or propyleneoxy group unit), aryloxy group, heterocyclic oxy group, acyloxy group, (alkoxy or aryloxy) carbonyloxy group, carbamoyloxy Group, sulfonyloxy group, amino group, (alkyl, aryl, or heterocyclic) amino group, acylamino group, sulfonamide group, ureido group, thioureido group, imide group, (alkoxy or aryloxy) carbonylamino group, sulfamoyl Amino group, semicarbazide group, thiosemicarbazide group, ammonio group, oxamoylamino group, N- (alkyl or aryl) sulfonylureido group, N-acylureido group, N-acylsulfamoylamino group, nitro Group, heterocyclic group containing a quaternized nitrogen atom (eg, pyridinio group, imidazolio group, quinolinio group, or isoquinolinio group), isocyano group, imino group, mercapto group, (alkyl, aryl, or heterocyclic) thio group , (Alkyl, aryl, or heterocyclic) dithio group, (alkyl or aryl) sulfonyl group, (alkyl or aryl) sulfinyl group, sulfo group or a salt thereof, sulfamoyl group, N-acylsulfamoyl group, N-sulfonylsulfuric group Examples include a famoyl group or a salt thereof, a phosphino group, a phosphinyl group, a phosphinyloxy group, a phosphinylamino group, and a silyl group. Here, the active methine group means a methine group substituted with two electron-withdrawing groups, and the electron-withdrawing group here means an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, An alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group, a trifluoromethyl group, a cyano group, a nitro group, or a carbonimidoyl group is meant.
Here, the two electron withdrawing groups may be bonded to each other to form a cyclic structure. The salt means a cation such as alkali metal, alkaline earth metal or heavy metal, or an organic cation such as ammonium ion or phosphonium ion. These substituents may be further substituted with these substituents. Y may further have a group represented by Z as a substituent.

The reason why the hot solvent exhibits the effect of the present invention is that the hot solvent melts near the development temperature so that it is compatible with the substance involved in development and can react at a lower temperature than when no hot solvent is added. It is thought to be because. Since heat development is a reduction reaction involving a relatively polar carboxylic acid or a silver ion transporter, it is preferable to form a reaction field having an appropriate polarity with a thermal solvent having a polar group. .
The melting point of the thermal solvent of the present invention is from 50 ° C. to 200 ° C., preferably from 60 ° C. to 150 ° C. In particular, in a photothermographic material that emphasizes stability against an external environment such as image storage stability, which is the object of the present invention, a thermal solvent having a melting point of 100 ° C. or higher and 150 ° C. or lower is preferable.

Although the specific example of the thermal solvent of this invention is shown below, the content of this invention is not limited by this. The parentheses indicate melting points.
N-methyl-N-nitroso-p-toluenesulfonamide (61 ° C.), 1,8-octanediol (62 ° C.), phenyl benzoate (67 ° C. to 71 ° C.), hydroquinone diethyl ether (67 ° C. to 73 ° C.) , Ε-caprolactam (68 ° C to 70 ° C), diphenyl phosphate (6 ° C to 8 ° C to 70 ° C), (±) -2-hydroxyoctanoic acid (68 ° C to 71 ° C), (±) -3-hydroxydodecane Acid (68 ° C to 71 ° C), 5-chloro-2-methylbenzothiazole (68 ° C to 71 ° C), β-naphthyl acetate (68 ° C to 71 ° C), batyl alcohol (68 ° C to 73 ° C), (± ) -2-hydroxydecanoic acid (69 ° C. to 72 ° C.), 2,2,2-trifluoroacetamide (69 ° C. to 72 ° C.), pyrazole (69 ° C.), (±) -2-hydroxyundecanoic acid (70 ° C.) ~ 73 ), N, N-diphenylformamide (71 ° C. to 72 ° C.), dibenzyl disulfide (71 ° C. to 72 ° C.), (±) -3-hydroxyundecanoic acid (71 ° C. to 74 ° C.), 2,2′-dihydroxy -4-methoxybenzophenone (71 ° C.), 2,4-dinitrotoluene (71 ° C.), 2,4-dimethoxybenzaldehyde (71 ° C.), 2,6-di-t-butyl-4-methylphenol (71 ° C.) 2,6-dichlorobenzaldehyde (71 ° C), diphenyl sulfoxide (71 ° C), stearic acid (71 ° C), 2,5-dimethoxynitrobenzene (72 ° C to 73 ° C), 1,10-decanediol (72-74) ° C), (R)-(−)-3-hydroxytetradecanoic acid (72 ° C. to 75 ° C.), 2-tetradecylhexadecanoic acid (72 ° C. to 75 ° C.), 2-methyl Xinaphthalene (72 ° C to 75 ° C), methyl 3-hydroxy-2-naphthoate (72 ° C to 76 ° C), tristearin (73.5 ° C), dotriacontane (74 ° C to 75 ° C), flavanone (74 ° C to 78 ° C), 2,5-diphenyloxazole (74 ° C), 8-quinolinol (74 ° C), o-chlorobenzyl alcohol (74 ° C), oleic acid amide (75 ° C to 76 ° C), (±)- 2-hydroxydodecanoic acid (75 ° C to 78 ° C), n-hexatriacontane (75 ° C to 79 ° C), iminodiacetonitrile (75 ° C to 79 ° C), p-chlorobenzyl alcohol (75 ° C), diphenyl phthalate (75 ° C.), N-methylbenzamide (76 ° C. to 78 ° C.), (±) -2-hydroxytridecanoic acid (76 ° C. to 79 ° C.), 1,3-diphenyl-1,3-propyl Pandione (76 ° C to 79 ° C), N-methyl-p-toluenesulfonamide (76 ° C to 79 ° C), 3'-nitroacetophenone (76 ° C to 80 ° C), 4-phenylcyclohexanone (76 ° C to 80 ° C) , Eicosanoic acid (76 ° C), 4-chlorobenzophenone (77 ° C to 78 ° C), (±) -3-hydroxytetradecanoic acid (77 ° C to 80 ° C), 2-hexadecyloctadecanoic acid (77 ° C to 80 ° C) P-nitrophenyl acetate (77 ° C to 80 ° C), 4'-nitroacetophenone (77 ° C to 81 ° C), 12-hydroxystearic acid (77 ° C), α, α'-dibromo-m-xylene (77 ° C) ), 9-methylanthracene (78 ° C. to 81 ° C.), 1,4-cyclohexanedione (78 ° C.), m-diethylaminophenol (78 ° C.), m-nitrobenzoic acid methyl ester (±) -2-hydroxytetradecanoic acid (79 ° C. to 82 ° C.), 1- (phenylsulfonyl) indole (79 ° C.), di-p-tolylmethane (79 ° C.), propionamide (79 ° C.) ), (±) -3-hydroxytridecanoic acid (80 ° C to 83 ° C), guaiacol glycerol ether (80 ° C to 85 ° C), octanoyl-N-methylglucamide (80 ° C to 90 ° C), o-fluoroacetanilide (80 ° C), acetoacetanilide (80 ° C), docosanoic acid (81 ° C to 82 ° C), p-bromobenzophenone (81 ° C),
Triphenylphosphine (81 ° C), dibenzofuran (82.8 ° C), (±) -2-hydroxypentadecanoic acid (82 ° C to 85 ° C), 2-octadecyleicosanoic acid (82 ° C to 85 ° C), 1,12 -Dodecanediol (82 ° C), methyl 3,4,5-trimethoxybenzoate (83 ° C), p-chloronitrobenzene (83 ° C), (±) -3-hydroxyhexadecanoic acid (84 ° C to 85 ° C), o -Hydroxybenzyl alcohol (84 ° C to 86 ° C), 1-triacontanol (84 ° C to 88 ° C), o-aminobenzyl alcohol (84 ° C), 4-methoxybenzyl acetate (84 ° C), (±) -2 -Hydroxyhexadecanoic acid (85 ° C to 88 ° C), m-dimethylaminophenol (85 ° C), p-dibromobenzene (86 ° C to 87 ° C), 2,5-dihydride Methyl xybenzoate (86 ° C to 88 ° C), (±) -3-hydroxypentadecanoic acid (86 ° C to 89 ° C), 4-benzylbiphenyl (86 ° C), p-fluorophenylacetic acid (86 ° C), 1, 14-tetradecanediol (87 ° C. to 89 ° C.), 2,5-dimethyl-2,5-hexanediol (87 ° C. to 90 ° C.), p-pentylbenzoic acid (87 ° C. to 91 ° C.), acetic acid α- (trichloro Methyl) benzyl (88 ° C. to 89 ° C.), 4,4′-dimethylbenzoin (88 ° C.), diphenyl carbonate (88 ° C.), m-dinitrobenzene (89.57 ° C.), (3R, 5R)-(+) -2,6-dimethyl-3,5-heptanediol (90 ° C to 93 ° C), (3S, 5S)-(-)-2,6-dimethyl-3,5-heptanediol (90 ° C to 93 ° C) , Cyclohexanone Shim (90 ° C.), p-bromoiodobenzene (91 ° C. to 92 ° C.), 4,4′-dimethylbenzophenone (92 ° C. to 95 ° C.), triphenylmethane (92 ° C. to 95 ° C.), stearic acid anilide (92 ° C to 96 ° C), p-hydroxyphenylethanol (92 ° C), monoethylurea, (92 ° C),
Acenaphthylene (93.5 ° C to 94.5 ° C), m-hydroxyacetophenone (93 ° C to 97 ° C), xylitol (93 ° C to 97 ° C), p-iodophenol (93 ° C), methyl p-nitrobenzoate ( 94 ° C to 98 ° C), p-nitrobenzyl alcohol (94 ° C), 1,2,4-triacetoxybenzene (95 ° C to 100 ° C), 3-acetylbenzonitrile (95 ° C to 103 ° C), 2-cyano Ethyl 3,3-diphenylacrylate (95 ° C. to 97 ° C.), 16-hydroxyhexadecanoic acid (95 ° C. to 99 ° C.), D (−)-ribose (95 ° C.), o-benzoylbenzoic acid (95 ° C.) , Α, α′-dibromo-o-xylene (95 ° C.), benzyl (95 ° C.), iodoacetamide (95 ° C.), n-propyl p-hydroxybenzoate (96 ° C. to 97 ° C.) n-propyl p-hydroxybenzoate (96 ° C to 97 ° C), flavone (96 ° C to 97 ° C), 2-deoxy-D-ribose (96 ° C to 98 ° C), lauryl gallate (96 ° C to 99 ° C) 1-naphthol (96 ° C), 2,7-dimethylnaphthalene (96 ° C), 2-chlorophenylacetic acid (96 ° C), acenaphthene (96 ° C), dibenzyl terephthalate (96 ° C), fumaronitrile (96 ° C), 4 '-Amino-2', 5'-diethoxybenzanilide (97 ° C to 100 ° C), phenoxyacetic acid (97 ° C to 100 ° C), 2,5-dimethyl-3-hexyne-2,5-diol (97 ° C) ), D-sorbitol (97 ° C), m-aminobenzyl alcohol (97 ° C), diethyl acetamidomalonate (97 ° C), 1,10-phenanthroline monohydrate (98 ° C to 10 ° C). 0 ° C.), 2-hydroxy-4-methoxy-4′-methylbenzophenone (98 ° C. to 100 ° C.),
2-bromo-4′-chloroacetophenone (98 ° C.), methylurea (98 ° C.), 4-phenoxyphthalonitrile (99 ° C. to 100 ° C.), o-methoxybenzoic acid (99 ° C. to 100 ° C.), p-butyl Benzoic acid (99 ° C to 100 ° C), xanthene (99 ° C to 100 ° C), pentafluorobenzoic acid (99 ° C to 101 ° C), phenanthrene (99 ° C), pt-butylphenol (100.4 ° C), 9 -Fluorenylmethanol (100 ° C to 101 ° C), 1,3-dimethylurea (100 ° C to 102 ° C), 4-acetoxyindole (100 ° C to 102 ° C), 1,3-cyclohexanedione (100 ° C), Stearic acid amide (100 ° C.), tri-m-tolylphosphine (100 ° C.), 4-biphenylmethanol (101 ° C. to 102 ° C.), 1,4-cyclohexane Xanthdiol (cis-, trans-mixture) (101 ° C), α, α'-dichloro-p-xylene (101 ° C), 2-t-butylanthraquinone (102 ° C), dimethyl fumarate (102 ° C), 3 , 3-dimethylglutaric acid (103 ° C. to 104 ° C.), 2-hydroxy-3-methyl-2-cyclopenten-1-one (103 ° C.), 4-chloro-3-nitroaniline (103 ° C.), N, N -Diphenylacetamide (103 ° C), 3 (2) -t-butyl-4-hydroxyanisole (104 ° C to 105 ° C), 4,4'-dimethylbenzyl (104 ° C to 105 ° C), 2,2-bis ( Hydroxymethyl) -2,2 ′, 2 ″ -nitrilotriethanol (104 ° C.), m-trifluoromethylbenzoic acid (104 ° C.), 3-pentanol (105 ° C. to 108 ° C.) , 2-methyl-1,4-naphthoquinone (105 ℃), α, α, α ', α'- tetrabromo -m- xylene (105 ° C.), 4-chlorophenyl acetic acid (106 ° C.),
4,4′-difluorobenzophenone (107.5 ° C. to 108.5 ° C.), 2,4-dichloro-1-naphthol (107 ° C. to 108 ° C.), L-ascorbyl palmitate (107 ° C. to 117 ° C.) 2,4-dimethoxybenzoic acid (108 ° C to 109 ° C), o-trifluoromethylbenzoic acid (108 ° C to 109 ° C), p-hydroxyacetophenone (109 ° C), dimethyl sulfone (109 ° C), 2,6 -Dimethylnaphthalene (110 ° C to 111 ° C), 2,3,5,6-tetramethyl-1,4-benzoquinone (110 ° C), tridecanedioic acid (110 ° C), triphenylchloromethane (110 ° C), fluoranthene (110 ° C), laurinamide (110 ° C), 1,4-benzoquinone (111 ° C), 3-benzylindole (111 ° C), Solcinol (111 ° C), 1-bromobutane (112.3 ° C), 2,2-bis (bromomethyl) -1,3-propanediol (112 ° C to 114 ° C), p-ethylbenzoic acid (113.5 ° C), 1,4-diacetoxy-2-methylnaphthalene (113 ° C.), 1-ethyl-2,3-piperazinedione (113 ° C.), 4-methyl-2-nitroaniline (113 ° C.), L-ascorbic acid dipalmitic acid Ester (113 ° C.), o-phenoxybenzoic acid (113 ° C.), p-nitrophenol (113 ° C.), methyl (diphenyl) phosphine oxide (113 ° C.), cholesterol acetate (114 ° C. to 115 ° C.), 2,6 -Dimethylbenzoic acid (114 ° C to 116 ° C), 3-nitrobenzonitrile (114 ° C), m-nitroaniline (114 ° C),
Ethyl α-D-glucoside (114 ° C.), acetanilide (115 ° C. to 116 ° C.), (±) -2-phenoxypropionic acid (115 ° C.), 4-chloro-1-naphthol (116 ° C. to 117 ° C.), p -Nitrophenylacetonitrile (116 ° C to 117 ° C), ethyl p-hydroxybenzoate (116 ° C), p-isopropylbenzoic acid (117 ° C to 118 ° C), D (+)-galactose (118 ° C to 120 ° C), o-dinitrobenzene (118 ° C), benzyl p-benzyloxybenzoate (118 ° C), 1,3,5-tribromobenzene (119 ° C), 2,3-dimethoxybenzoic acid (120 ° C to 122 ° C), 4-chloro-2-methylphenoxyacetic acid (120 ° C.), meso-erythritol (121.5 ° C.), 9,10-dimethyl-1,2-benz Anthracene (122 ° C to 123 ° C), 2-naphthol (122 ° C), N-phenylglycine (122 ° C), bis (4-hydroxy-3-methylphenyl) sulfide (122 ° C), p-hydroxybenzyl alcohol (124 5 ° C to 125.5 ° C), 2 ', 4'-dihydroxy-3'-propylacetophenone (124 ° C to 127 ° C), 1,1-bis (4-hydroxyphenyl) ethane (124 ° C), m- Fluorobenzoic acid (124 ° C), diphenylsulfone (124 ° C), 2,2-dimethyl-3-hydroxypropionic acid (125 ° C), 3,4,5-trimethoxycinnamic acid (125 ° C), o-fluorobenzoic acid Acid (126.5 ° C.), isonitrosoacetophenone (126 ° C. to 128 ° C.), 5-methyl-1,3-cyclohexanedione (126 ), 4-benzoylbutyric acid (127 ° C), methyl p-hydroxybenzoate (127 ° C), p-bromonitrobenzene (127 ° C), 3,4-dihydroxyphenylacetic acid (128 ° C to 130 ° C), 5α-cholestane- 3-one (128 ° C to 130 ° C), 6-bromo-2-naphthol (128 ° C), isobutyramide (128 ° C), 1-naphthylacetic acid (129 ° C),
2,2-dimethyl-1,3-propanediol (129 ° C), p-diiodobenzene (129 ° C), dodecanedioic acid (129 ° C), 4,4'-dimethoxybenzyl (131 ° C to 133 ° C), Dimethylol urea (132.5 ° C), o-ethoxybenzamide (132 ° C to 134 ° C), sebacic acid (132 ° C), p-toluenesulfonamide (134 ° C), salicylanilide (135 ° C), β-sitosterol (136) ° C to 137 ° C), 1,2,4,5-tetrachlorobenzene (136 ° C), 1,3-bis (1-hydroxy-1-methylethyl) benzene (137 ° C), phthalonitrile (138 ° C), 4 -N-propylbenzoic acid (139 ° C), 2,4-dichlorophenoxyacetic acid (140.5 ° C), 2-naphthylacetic acid (140 ° C), methyl terephthalate 140 ° C), 2,2-dimethylsuccinic acid (141 ° C), 2,6-dichlorobenzonitrile (142.5 ° C to 143.5 ° C), o-chlorobenzoic acid (142 ° C), 1,2-bis (Diphenylphosphino) ethane (143 ° C. to 144 ° C.), α, α, α-tribromomethylphenyl sulfone (143 ° C.), D (+)-xylose (144 ° C. to 145 ° C.), phenylurea (146 ° C.) N-propyl gallate (146 ° C.), 4,4′-dichlorobenzophenone (147 ° C. to 148 ° C.), 2 ′, 4′-dihydroxyacetophenone (147 ° C.), cholesterol (148.5 ° C.), 2-methyl -1-pentanol (148 ° C.), 4,4′-dichlorodiphenyl sulfone (148 ° C.), diglycolic acid (148 ° C.), adipic acid (149 ° C. to 150 ° C.), 2-de Carboxymethyl -D- glucose (149 ° C.), diphenyl acetic acid (149 ℃), o- bromobenzoic acid (0.99 ° C.).

Amount of thermal solvent in the present invention is preferably 0.01 g / m ² or more 5.0 g / m ² or less, more preferably 0.05 g / m ² or more 2.5 g / m ² or less, more preferably Is 0.1 g / m ² or more and 1.5 g / m ² or less. The thermal solvent is preferably contained in the image forming layer.
Moreover, although the said thermal solvent may be used independently, you may use it in combination of 2 or more type.

In the present invention, the thermal solvent may be contained in the coating solution by any method such as a solution form, an emulsified dispersion form, or a solid fine particle dispersion form, and may be contained in the photothermographic material.
Well-known emulsifying dispersion methods include dissolving oil using an oil such as dibutyl phthalate, tricresyl phosphate, glyceryl triacetate or diethyl phthalate, or an auxiliary solvent such as ethyl acetate or cyclohexanone, and mechanically dispersing the emulsified dispersion. The method of producing is mentioned.

As the solid fine particle dispersion method, the powder of the hot solvent is dispersed in an appropriate solvent such as water by a ball mill, a colloid mill, a vibration ball mill, a sand mill, a jet mill, a roller mill or ultrasonic waves to produce a solid dispersion. A method is mentioned. In this case, a protective colloid (for example, polyvinyl alcohol) or a surfactant (for example, an anionic surfactant such as sodium triisopropylnaphthalenesulfonate (a mixture of three isopropyl groups having different substitution positions)) may be used. Good. In the mills, beads such as zirconia are usually used as a dispersion medium, and Zr and the like eluted from these beads may be mixed in the dispersion. Although it depends on the dispersion conditions, it is usually in the range of 1 ppm to 1000 ppm. If the Zr content in the light-sensitive material is 0.5 mg or less per 1 g of silver, there is no practical problem.
The aqueous dispersion preferably contains a preservative (for example, benzoisothiazolinone sodium salt). In the present invention, the hot solvent is preferably used as a solid dispersion.

(Other additives)
1) Mercapto, disulfide, and thiones In the present invention, mercapto compounds and disulfide compounds are used for the purpose of controlling development by suppressing or promoting development, improving spectral sensitization efficiency, and improving storage stability before and after development. And thione compounds, paragraphs 0067 to 0069 of JP-A-10-62899, compounds represented by formula (I) of JP-A-10-186572, and specific examples thereof include paragraph numbers 0033 to 0052. , European Patent Publication No. 0803764A1, page 20, lines 36-56. Of these, mercapto-substituted heteroaromatic compounds described in JP-A-9-297367, JP-A-9-304875, JP-A-2001-100388, JP-A-2002-303954, JP-A-2002-303951, and the like are preferable. .

2) Toning agent In the photothermographic material of the invention, it is preferable to add a toning agent. The color toning agent used in the present invention can be used without particular limitation as long as it is a color toning agent that has been used in a photothermographic material utilizing an organic silver salt. The toning agent may be a so-called precursor that is derivatized so as to have an effective function only during development. For example, JP-A-46-6077, 47-10282, 49-5019, 49-5020, 49-91215, 49-91215, 50-2524 Gazette, 50-32927 gazette, 50-67132 gazette, 50-67641 gazette, 50-114217 gazette, 51-3223 gazette, 51-27923 gazette, 52-14788 gazette. JP, 52-99813, 53-1020, 53-76020, 54-156524, 54-156525, 61-183642, JP-A-4-56848. Gazette, Japanese Patent Publication Nos. 49-10727, 54-20333, U.S. Pat. No. 3,080,254, 3,446, No. 48, No. 3,782,941, No. 4,123,282, No. 4,510,236, British Patent No. 1,380,795, Those disclosed in Belgian Patent No. 841,910 and the like can be used as appropriate.

Specific examples of toning agents include phthalimide and N-hydroxyphthalimide; succinimide, pyrazolin-5-one, and quinazolinone, 3-phenyl-2-pyrazolin-5-one, 1-phenylurazol, quinazoline and 2,4- Cyclic imides such as thiazolidinediones; naphthalimides (eg N-hydroxy-1,8-naphthalimide); cobalt complexes (eg cobalt hexamine trifluoroacetate); 3-mercapto-1,2,4-triazole, 2 , 4-Dimercaptopyrimidine, 3-mercapto-4,5-diphenyl-1,2,4-triazole and mercaptans exemplified by 2,5-dimercapto-1,3,4-thiadiazole; N- (aminomethyl) Aryldicarboximides (e.g. (N, -Dimethylaminomethyl) phthalimide and N, N- (dimethylaminomethyl) -naphthalene-2,3-dicarboximide); and blocked pyrazoles, isothiuronium derivatives and certain photobleaching agents (for example N, N'- Hexamethylenebis (1-carbamoyl-3,5-dimethylpyrazole), 1,8- (3,6-diazaoctane) bis (isothiuronium trifluoroacetate) and 2-tribromomethylsulfonyl)-(benzothiazole)) And 3-ethyl-5-[(3-ethyl-2-benzothiazolinylidene) -1-methylethylidene] -2-thio-2,4-oxazolidinedione; phthalazinone, phthalazinone derivatives or metal salts, or 4 -(1-Naphthyl) phthalazinone, 6-chlorophthalazino Derivatives of 5,7-dimethoxyphthalazinone and 2,3-dihydro-1,4-phthalazinedione; phthalazinone and phthalic acid derivatives (eg phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachloro In combination with phthalic anhydride, etc .; phthalazine, phthalazine derivatives (for example, 4- (1-naphthyl) phthalazine, 6-chlorophthalazine, 5,7-dimethoxyphthalazine, 6-isobutylphthalazine, 6-tert-butyl Derivatives such as phthalazine, 5,7-dimethylphthalazine, and 2,3-dihydrophthalazine) or metal salts;
Combinations of phthalazine and its derivatives and phthalic acid derivatives (eg, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid, tetrachlorophthalic anhydride, etc.); quinazolinedione, benzoxazine or naphthoxazine derivatives; only as a color modifier Rhodium complexes that also serve as a source of halide ions for in situ silver halide formation, such as ammonium hexachlororhodium (III), rhodium bromide, rhodium nitrate and potassium hexachlororhodium (III); Oxides and persulfates such as ammonium disulfide and hydrogen peroxide; 1,3-benzoxazine-2,4-dione, 8-methyl-1,3-benzoxazine-2,4-dione and 6 -Nitro-1,3-benzoxazine-2,4-di Benzoxazine-2,4-diones such as thiones; pyrimidines and asymmetric-triazines (eg 2,4-dihydroxypyrimidine, 2-hydroxy-4-aminopyrimidine etc.), azauracil, and tetraazapentalene derivatives (eg 3,6-dimercapto-1,4-diphenyl-1H, 4H-2,3a, 5,6a-tetraazapentalene, and 1,4-di (o-chlorophenyl) -3,6-dimercapto-1H, 4H -2,3a, 5,6a-tetraazapentalene) and the like.

  In the present invention, it is particularly preferable to use a phthalazine derivative represented by the following formula (I) as a color tone. In the formula (I), R represents a substituent, and m represents an integer of 1 to 6. When m ≧ 2, the plurality of R may be the same or different.

As the substituent represented by R, any substituent may be used as long as it does not adversely affect photographic properties. For example, a halogen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom), linear, branched or cyclic alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 1 carbon atoms). 12, for example, methyl, ethyl, isopropyl, tert-butyl, tert-octyl, tert-amyl, cyclohexyl, etc.), an alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms). , Particularly preferably 2 to 12, and examples thereof include vinyl, allyl, 2-butenyl, and 3-pentenyl.), An aryl group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly Preferably, it is 6 to 12, and examples thereof include phenyl, p-methylphenyl, naphthyl and the like. Si group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms such as methoxy, ethoxy and butoxy), aryloxy group (preferably having carbon atoms) 6-30, more preferably 6-20, particularly preferably 6-12, for example, phenyloxy, 2-naphthyloxy, etc.), acyloxy groups (preferably having 1-20 carbon atoms, more preferably 2 to 16, particularly preferably 2 to 12, for example, acetoxy, benzoyloxy, etc.), amino group (preferably having 0 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 12 carbon atoms). Dimethylamino group, diethylamino group, dibutylamino group, etc.), acylamino group (preferably carbon 1-20, more preferably 2 to 16, particularly preferably 2 to 12, e.g., acetylamino or benzoylamino.),
A sulfonylamino group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms such as methanesulfonylamino and benzenesulfonylamino), a ureido group (preferably carbon The number is 1 to 20, more preferably 1 to 16, particularly preferably 1 to 12, and examples thereof include ureido, methylureido, and phenylureido), carbamate groups (preferably having 2 to 20 carbon atoms, and more). Preferably they are 2-16, Most preferably, it is 2-12, for example, a methoxycarbonylamino, phenyloxycarbonylamino etc. are mentioned), a carboxyl group, a carbamoyl group (preferably C1-C20, More preferably 1 To 16, particularly preferably 1 to 12, for example, carbamoyl, N, -Diethylcarbamoyl, N-phenylcarbamoyl, etc.), alkoxycarbonyl groups (preferably having 2-20 carbon atoms, more preferably 2-16, particularly preferably 2-12, such as methoxycarbonyl, ethoxy Carbonyl, etc.), an acyl group (preferably having 2-20 carbon atoms, more preferably 2-16, particularly preferably 2-12, and examples thereof include acetyl, benzoyl, formyl, and pivaloyl. ), A sulfo group, a sulfonyl group (preferably having a carbon number of 1-20, more preferably 1-16, particularly preferably 1-12, such as mesyl, tosyl, etc.), a sulfamoyl group (preferably carbon Number 0 to 20, more preferably 0 to 16, particularly preferably 0 to 12, for example Sulfamoyl, methylsulfamoyl, dimethylsulfamoyl, phenylsulfamoyl, etc.), cyano group, nitro group, hydroxyl group, mercapto group, alkylthio group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16, particularly preferably 1 to 12, for example, methylthio, butylthio, etc.), heterocyclic group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms). And examples thereof include pyridyl, imidazolyl, pyrrolidyl, and the like.

  The substituent represented by R is preferably a halogen atom, a linear, branched or cyclic alkyl group, an aryl group, an alkoxy group, an aryloxy group, a cyano group, a nitro group, a hydroxyl group, a mercapto group, or an alkylthio group. More preferably a linear, branched or cyclic alkyl group, an alkoxy group, or an aryloxy group, and particularly preferably a linear or branched alkyl group.

  When m is 2 or more, the substituents represented by R may be the same as or different from each other, and these substituents may be further substituted with another substituent. Moreover, it may combine with each other to form an annular structure.

  As the compound represented by the formula (I), a compound having a melting point of 130 ° C. or lower is further preferable, and this compound includes those which are liquid at normal temperature (temperature of about 15 ° C.).

  Specific examples of the compound represented by formula (I) and having a melting point of 130 ° C. or lower are given below, but the compounds that can be used in the present invention are not limited to these specific examples. .

The amount of the color toning agent used in the photothermographic material of the present invention is an amount sufficient to improve the image performance to a desired degree. Use of an appropriate amount of the color tone is advantageous in increasing the image density and forming a black silver image. The color toning agent is preferably contained at 0.1 mol% or more and 50 mol% or less, more preferably 0.5 mol% or more and 20 mol% or less per 1 mol of silver on the side having the image forming layer.
The color toning agent may be added to any layer as long as it has the image forming layer, but is preferably added to the image forming layer and / or a layer adjacent to the layer. Is when added to the image forming layer.

3) Color tone adjusting agent The heat-developable recording material of the present invention preferably contains a color tone adjusting agent for adjusting the color tone of developed silver. The color tone adjuster is an additive that adjusts the color tone of developed silver to a desired color tone.For example, when a pure black tone image is intended, a yellow oxidation product is produced when the developed silver tone is blue. It is preferable to use a reducing compound. In the case of developed silver having a yellowish brown color tone, it is preferable to use a cyan color developing compound as the color tone adjusting agent. In addition, the color of the color tone adjusting agent may be adjusted according to the color tone generated by the developed silver and the target image color tone.
1) Color Tone Adjusting Agent Represented by General Formula (P) As one of the color tone adjusting agents that can be used in the present invention, a compound represented by general formula (P) is preferably included.

In the formula, R ²¹ and R ²² each independently represents a hydrogen atom, an alkyl group or an acylamino group. However, R ²¹ and R ²² are not each a 2-hydroxyphenylmethyl group and are not simultaneously a hydrogen atom. R ²³ represents a hydrogen atom or an alkyl group. R ²⁴ represents a substituent substitutable on the benzene ring.

When R ²¹ is an alkyl group, an alkyl group having 1 to 30 carbon atoms is preferable, and an alkyl group having 1 to 10 carbon atoms is more preferable.
The alkyl group may have a substituent. Specifically, the unsubstituted alkyl group is preferably a methyl, ethyl, butyl, octyl, isopropyl, t-butyl, t-octyl, t-amyl, sec-butyl, cyclohexyl, or 1-methyl-cyclohexyl group. A group sterically larger than the isopropyl group (for example, an isopropyl group, an isononyl group, a t-butyl group, a t-amyl group, a t-octyl group, a cyclohexyl group, a 1-methyl-cyclohexyl group, or an adamantyl group). More preferably, a tertiary alkyl group such as t-butyl, t-octyl, or t-amyl group is particularly preferable.
In addition, when the alkyl group has a substituent, the substituent is a halogen atom, aryl group, alkoxy group, amino group, acyl group, acylamino group, alkylthio group, arylthio group, sulfonamide group, acyloxy group, oxycarbonyl Group, carbamoyl group, sulfamoyl group, sulfonyl group, phosphoryl group and the like.

When R ²² is an alkyl group, an alkyl group having 1 to 30 carbon atoms is preferable, and an unsubstituted alkyl group having 1 to 24 carbon atoms is more preferable.
The alkyl group may have a substituent. Specifically, an unsubstituted alkyl group is preferably a methyl, ethyl, butyl, octyl, isopropyl, t-butyl, t-octyl, t-amyl, sec-butyl, cyclohexyl, or 1-methyl-cyclohexyl group.
Examples of the substituent are the same as R21.

When R ²¹ and R ²² are an acylamino group, an acylamino group having 1 to 30 carbon atoms is preferable, and an acylamino group having 1 to 10 carbon atoms is more preferable.
The acylamino group may be unsubstituted or may have a substituent. Specific examples include an acetylamino group, an alkoxyacetylamino group, and an aryloxyacetylamino group.

R ²¹ is preferably an alkyl group among a hydrogen atom, an alkyl group, and an acylamino group.
On the other hand, R ²² is preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 24 carbon atoms among a hydrogen atom, an alkyl group or an acylamino group, specifically, a methyl group, an isopropyl group, and t-butyl. Note that R ²¹ and R ²² are not 2-hydroxyphenylmethyl groups, and are not hydrogen atoms at the same time.

R ²³ represents a hydrogen atom or an alkyl group, and among them, a hydrogen atom or an alkyl group having 1 to 30 carbon atoms is preferable, and a hydrogen atom or an unsubstituted alkyl group having 1 to 24 carbon atoms is more preferable. The description of the alkyl group is the same as R ²² . Specific examples include a methyl group, an isopropyl group, and a t-butyl group.
One of R ²² and R ²³ is preferably a hydrogen atom.

R ²⁴ represents a group that can be substituted on the benzene ring, and is the same group as described for R ¹² and R ^{12 ′} of the compound of the general formula (R). R ²⁴ is preferably a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms or an oxycarbonyl group having 2 to 30 carbon atoms, and more preferably an alkyl group having 1 to 24 carbon atoms. Examples of the substituent of the alkyl group include an aryl group, amino group, alkoxy group, oxycarbonyl group, acylamino group, acyloxy group, imide group, and ureido group, and aryl group, amino group, oxycarbonyl group, or alkoxy group. Is more preferable.

  A more preferable structure of the compound of the general formula (P) is represented by the following general formula (P-2).

In the formula, R ³¹ , R ³² , R ³³ and R ³⁴ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms. R ³¹ and R ³² , R ³³ and R ³⁴ are not simultaneously hydrogen atoms. R ³¹ , R ³² , R ³³ and R ³⁴ are preferably each independently an alkyl group having 1 to 10 carbon atoms. The substituent of the alkyl group is not particularly limited, but preferably an aryl group, a hydroxy group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acylamino group, a sulfonamido group, a sulfonyl group, a phosphoryl group, Examples include an acyl group, a carbamoyl group, an ester group, and a halogen atom. Among them, a group sterically larger than the isopropyl group (for example, isopropyl group, isononyl group, t-butyl group, t-amyl group, t-octyl group, cyclohexyl group, 1-methyl-cyclohexyl group, adamantyl group, etc.) Is preferably at least one, more preferably two or more. A tertiary alkyl group that is sterically larger than the isopropyl group, such as t-butyl, t-octyl, or t-amyl group, is particularly preferable.

L is preferably a —CHR ¹³ — group.
R ¹³ is preferably a hydrogen atom or an alkyl group having 1 to 15 carbon atoms. As the alkyl group, a cyclic alkyl group is also preferably used in addition to a chain alkyl group. Moreover, what has a C = C bond in these alkyl groups can also be used preferably. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a 2,4,4-trimethylpentyl group, a cyclohexyl group, a 2,4-dimethyl-3-cyclohexenyl group, or 3,5-dimethyl-3. -A cyclohexenyl group and the like are preferable. R ¹³ is particularly preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, or a 2,4-dimethyl-3-cyclohexenyl group.

When R ¹¹ and R ¹¹ ′ are tertiary alkyl groups and R ¹² and R ¹² ′ are methyl groups, R ¹³ is a primary or secondary alkyl group having 1 to 8 carbon atoms (methyl group, ethyl group, propyl group). Group, isopropyl group, or 2,4-dimethyl-3-cyclohexenyl group).
When R ¹¹ and R ¹¹ ′ are tertiary alkyl groups and R ¹² and R ¹² ′ are alkyl groups other than methyl groups, R ¹³ is preferably a hydrogen atom.
When R ¹¹ and R ¹¹ ′ are not a tertiary alkyl group, R ¹³ is preferably a hydrogen atom or a secondary alkyl group, and particularly preferably a secondary alkyl group. A preferred group as the secondary alkyl group for R ¹³ is an isopropyl group or a 2,4-dimethyl-3-cyclohexenyl group.

  Specific examples of the compounds represented by the general formula (P) and the general formula (P-2) in the present invention are shown below, but are not limited thereto.

2) Couplers Another color tone adjusting agent is a coupler that develops color by coupling with an oxidation product of a reducing agent in heat development. These couplers are described in JP-A Nos. 2002-311533, 2002-328444, 2002-318432, 2002-221768, 2002-287296, and 2002-296931. A desired color can be obtained by a combination of a reducing agent and a coupler.

  The color tone adjusting agent may be contained in the coating solution by any method such as a solution form, an emulsified dispersion form, or a solid fine particle dispersion form, and may be contained in the photothermographic material.

Examples of the emulsification dispersion method include a method in which an emulsion such as dibutyl phthalate, tricresyl phosphate, glyceryl triacetate or diethyl phthalate is dissolved using an auxiliary solvent such as ethyl acetate or cyclohexanone to mechanically prepare an emulsion dispersion. It is done.
Examples of the solid fine particle dispersion method include a method in which a powder of a compound is dispersed in a suitable solvent such as water by a ball mill, a colloid mill, a vibration ball mill, a sand mill, a jet mill, a roller mill, or an ultrasonic wave to prepare a solid dispersion. It is done. In this case, a protective colloid (for example, polyvinyl alcohol) or a surfactant (for example, an anionic surfactant such as sodium triisopropylnaphthalenesulfonate (a mixture of three isopropyl groups having different substitution positions)) may be used. Good. The aqueous dispersion can contain a preservative (eg, benzoisothiazolinone sodium salt).

  The color tone adjusting agent is preferably contained in the image forming layer containing the organic silver salt, but one may be contained in the image forming layer and the other may be contained in the non-image forming layer adjacent to the image forming layer. You may make it contain in a layer. Further, when the image forming layer is composed of a plurality of layers, they may be contained in separate layers.

  The addition amount ratio (molar ratio) of the color tone adjusting agent to the reducing agent represented by the general formula (R) is preferably in the range of 0.001 to 0.2, and in the range of 0.005 to 0.1. It is more preferable that it is in the range of 0.008 to 0.05.

4) Plasticizer In the present invention, a known plasticizer can be used to improve film physical properties. Regarding the plasticizer that can be used in the image forming layer and the non-photosensitive layer, JP-A No. 11-65021, paragraph No. 0117, JP-A No. 2000-5137, JP-A No. 2004-219794, JP-A No. 2004-21802, and JP-A No. 2004. The compounds described in No. 334077 are preferred.

5) Dye and Pigment In the image forming layer of the present invention, various dyes and pigments (for example, CI Pigment Blue 60, CI, etc.) are used from the viewpoints of color tone improvement, prevention of interference fringes during laser exposure, and prevention of irradiation. Pigment Blue 64, CI Pigment Blue 15: 6) can be used. These are described in detail in WO98 / 36322, JP-A-10-268465, JP-A-11-338098 and the like.

5) Super-high contrast agent For the formation of a super-high contrast image suitable for printing plate making, it is preferable to add a super-high contrast agent to the image forming layer. Regarding the super-thinning agent and the addition method and amount thereof, paragraphs No. 0118 of JP-A No. 11-65021, paragraph Nos. 0136 to 0193 of JP-A No. 11-223898, JP-A No. 2000-284399 (H ), Formulas (1) to (3), compounds of formulas (A) and (B), compounds of general formulas (III) to (V) described in Japanese Patent Application No. 11-91652 (specific compounds: 21 to 24) and the high contrast accelerator are described in paragraph No. 0102 of JP-A No. 11-65021 and paragraph Nos. 0194 to 0195 of JP-A No. 11-223898.

  In order to use formic acid or formate as a strong fogging substance, it is preferably contained in an amount of 5 mmol or less, more preferably 1 mmol or less per mol of silver on the side having an image forming layer containing photosensitive silver halide.

When the ultrahigh contrast agent is used in the photothermographic material of the invention, it is preferable to use an acid formed by hydrating diphosphorus pentoxide or a salt thereof in combination. Acids or salts thereof formed by hydration of diphosphorus pentoxide include metaphosphoric acid (salt), pyrophosphoric acid (salt), orthophosphoric acid (salt), triphosphoric acid (salt), tetraphosphoric acid (salt), hexametalin An acid (salt) etc. can be mentioned. Examples of the acid or salt thereof formed by hydrating diphosphorus pentoxide particularly preferably include orthophosphoric acid (salt) and hexametaphosphoric acid (salt). Specific examples of the salt include sodium orthophosphate, sodium dihydrogen orthophosphate, sodium hexametaphosphate, and ammonium hexametaphosphate.
The amount of acid or salt thereof formed by hydrating diphosphorus pentoxide (the coating amount per 1 m ^{2 of the} photosensitive material) may be a desired amount according to the performance such as sensitivity and fogging, but 0.1 mg / m ² It is preferably 500 mg / m ² or less, more preferably 0.5 mg / m ² or more and 100 mg / m ² or less.

(Preparation and application of coating solution)
The preparation temperature of the image forming layer coating solution in the invention is preferably from 30 ° C. to 65 ° C., more preferably from 35 ° C. to less than 60 ° C., and more preferably from 35 ° C. to 55 ° C. Moreover, it is preferable that the temperature of the image forming layer coating liquid immediately after the addition of the polymer latex is maintained at 30 ° C. or higher and 65 ° C. or lower.

(7) Other Layer Configurations and Components 1) Antihalation Layer In the photothermographic material of the invention, the antihalation layer can be provided on the side farther from the light source than the image forming layer.

As for the antihalation layer, paragraph numbers 0123 to 0124 of JP-A No. 11-65021, JP-A Nos. 11-223898, 9-230531, 10-36695, 10-104779, 11-231457, 11 -352625, 11-352626 and the like.
The antihalation layer contains an antihalation dye having absorption at the exposure wavelength. When the exposure wavelength is in the infrared region, an infrared absorbing dye may be used, and in that case, a dye having no absorption in the visible region is preferable.
When antihalation is performed using a dye having absorption in the visible range, it is preferable that the dye color does not substantially remain after image formation, and a means for decoloring by the heat of heat development is used. In particular, it is preferable to add a thermally decolorable dye and a base precursor to the non-photosensitive layer to function as an antihalation layer. These techniques are described in JP-A-11-231457.

The amount of decoloring dye added is determined by the use of the dye. In general, the optical density (absorbance) measured at the target wavelength is used in an amount exceeding 0.1. The optical density is preferably 0.15 to 2, and more preferably 0.2 to 1. The amount of dye used to obtain such an optical density is generally about 0.001 g / m ^{2 to} 1 g / m ² .

If the dye is decolored in this way, the optical density after heat development can be reduced to 0.1 or less. Two or more kinds of decoloring dyes may be used in combination in a heat decoloring type recording material or a photothermographic material. Similarly, two or more kinds of base precursors may be used in combination.
In the thermal decoloration using such decoloring dye and base precursor, a substance (for example, diphenylsulfone, which lowers the melting point by 3 ° C. (deg) or more when mixed with a base precursor as described in JP-A No. 11-352626). 4-Chlorophenyl (phenyl) sulfone), 2-naphthyl benzoate and the like are preferably used in view of thermal decoloring properties.

2) Back Layer Back layers that can be applied to the present invention are described in paragraph Nos. 0128 to 0130 of JP-A No. 11-65021.

  In the present invention, a colorant having an absorption maximum at 300 nm to 450 nm can be added for the purpose of improving the silver tone and the temporal change of the image. Such colorants are disclosed in JP-A-62-210458, JP-A-63-104046, JP-A-63-103235, JP-A-63-208846, JP-A-63-306436, JP-A-63-141435, and JP-A-01-61745. No. 1, Japanese Patent Laid-Open No. 2001-100363, and the like.

  The photothermographic material of the present invention is a so-called single-sided photosensitive material having an image forming layer containing at least one silver halide emulsion on one side of a support and a back layer on the other side. preferable.

3) pH of membrane surface
The photothermographic material of the present invention preferably has a film surface pH of 7.0 or less, more preferably 6.6 or less before heat development. The lower limit is not particularly limited, but is about 3. The most preferred pH range is in the range of 4 to 6.2. For the adjustment of the film surface pH, it is preferable to use an organic acid such as a phthalic acid derivative, a non-volatile acid such as sulfuric acid, and a volatile base such as ammonia from the viewpoint of reducing the film surface pH. In particular, ammonia is volatile and is preferable for achieving a low film surface pH because it can be removed before the coating process or thermal development.
Further, it is also preferable to use ammonia and a non-volatile base such as sodium hydroxide, potassium hydroxide or lithium hydroxide in combination. In addition, the measuring method of film surface pH is described in paragraph number 0123 of Unexamined-Japanese-Patent No. 2000-284399.

4) Hardener A hardener may be used for each layer such as the image forming layer, protective layer, and back layer in the present invention. Examples of hardeners include T.W. H. There are various methods described in "THE THEORY OF THE PHOTOGRAPHIC PROCESS FOURTH EDITION" by James (published by Macmillan Publishing Co., Inc., published in 1977), pages 77 to 87, Chrome Alum, 2,4-dichloro-6 In addition to hydroxy-s-triazine sodium salt, N, N-ethylenebis (vinylsulfoneacetamide), N, N-propylenebis (vinylsulfoneacetamide), polyvalent metal ions described on page 78 of the same document, US Pat. No. 4,281 , 060, and JP-A-6-208193, epoxy compounds such as US Pat. No. 4,791,042, and vinylsulfone compounds such as JP-A-62-289048 are preferably used.

  The hardening agent is added as a solution, and the addition time of this solution into the protective layer coating solution is from 180 minutes before to immediately before application, preferably from 60 minutes to 10 seconds before application. As long as the effects of the present invention are sufficiently exhibited, there is no particular limitation. Specific mixing methods include mixing in a tank in which the average residence time calculated from the addition flow rate and the amount of liquid fed to the coater is a desired time, and N.I. Harnby, M.M. F. Edwards, A.D. W. There is a method using a static mixer described in Chapter 8 of Nienow's “Liquid Mixing Technology” (Nikkan Kogyo Shimbun, 1989), translated by Koji Takahashi.

5) Antistatic agent In this invention, it is preferable to have a conductive layer containing a metal oxide or a conductive polymer. The antistatic layer may serve as an undercoat layer, a back layer surface protective layer, or the like, or may be provided separately.
Examples of the conductive polymer compound include polyvinylbenzene sulfonates, polyvinylbenzyltrimethylammonium chloride, US Pat. Nos. 4,108,802, 4,118,231, 4,126,467, 4, Quaternary salt polymers described in US Pat. No. 137,217, polymer latexes described in US Pat. No. 4,070,189, OLS 2,830,767, JP-A Nos. 61-296352, 61-62033, and the like. Can be used.
However, it is most preferable that the conductive layer of the present invention contains a conductive metal oxide in that the side resistance value of the photothermographic material can be sufficiently lowered.
Examples of metal oxides include ZnO, TiO ₂ and SnO _2. Addition of Al and In to ZnO, addition of Sb, Nb, P and halogen elements to SnO ₂ , and addition to TiO ₂ For example, addition of Nb, Ta or the like is preferable. In particular, SnO ₂ added with Sb is preferable. The amount of different atoms added is preferably in the range of 0.01 mol% to 30 mol%, more preferably in the range of 0.1 to 10 mol%. The shape of the metal oxide may be spherical, needle-like, or plate-like, but the long axis / uniaxial ratio is 2.0 or more, preferably 3.0 to 50 in terms of the effect of imparting conductivity. Good. Range amount preferably of 1mg / m ² ~1000mg / m ² of metal oxide, more preferably 10mg / m ² ~500mg / m ² range, more preferably at 20mg / m ² ~200mg / m ² It is a range. The antistatic layer in the present invention may be disposed on either the image forming layer surface side or the back surface side, but is preferably disposed between the support and the back layer. Specific examples of the antistatic layer are described in paragraph No. 0135 of JP-A No. 11-65021, JP-A Nos. 56-143430, 56-143431, 58-62646, No. 56-120519, and JP-A No. 11-84573. Paragraph Nos. 0040 to 0051, US Pat. No. 5,575,957, and paragraph Nos. 0078 to 0084 of JP-A-11-223898.

6) Support The transparent support is subjected to heat treatment in a temperature range of 130 ° C. to 185 ° C. in order to relieve internal strain remaining in the film during biaxial stretching and to eliminate heat shrinkage strain generated during heat development processing. Polyester, especially polyethylene terephthalate, is preferably used. In the case of a photothermographic material for medical use, the transparent support may be colored with a blue dye (for example, dye-1 described in Examples of JP-A-8-240877) or may be uncolored. Examples of the support include water-soluble polyesters disclosed in JP-A-11-84574, styrene-butadiene copolymers described in JP-A-10-186565, and vinylidene chloride described in JP-A-2000-39684 and Japanese Patent Application No. 11-106881, paragraphs 0063 to 0080. It is preferable to apply an undercoating technique such as a copolymer. When the image forming layer or the back layer is applied to the support, the moisture content of the support is preferably 0.5% by mass or less.

7) Other additives Antioxidants, stabilizers, plasticizers, ultraviolet absorbers or coating aids may be further added to the photothermographic material. Various additives are added to either the image forming layer or the non-photosensitive layer. Regarding these, WO 98/36322, EP 803764A1, JP-A-10-186567, 10-18568 and the like can be referred to.

8) Coating method The photothermographic material in the invention may be coated by any method. Specifically, various coating operations including extrusion coating, slide coating, curtain coating, dip coating, knife coating, flow coating, or extrusion coating using a hopper of the type described in US Pat. No. 2,681,294. And Stephen F. Kistler, Peter M. et al. The extrusion coating described in “LIQUID FILM COATING” (CHAPMAN & HALL, 1997) by Schweizer (1997), pages 399 to 536 is preferably used, and slide coating is particularly preferably used.
An example of the shape of a slide coater used for slide coating is shown in FIG. 11b. 1 If desired, two or more layers can be simultaneously coated by the method described on pages 399 to 536 of the same document, the method described in US Pat. No. 2,761,791 and British Patent No. 837,095. . In the present invention, particularly preferred coating methods are those described in JP-A Nos. 2001-194748, 2002-153808, 2002-153803, and 2002-182333.

The image forming layer coating solution in the present invention is preferably a so-called thixotropic fluid. Regarding this technique, JP-A-11-52509 can be referred to. In the image forming layer coating solution of the present invention, the viscosity at a shear rate of 0.1 S ⁻¹ is preferably 400 mPa · s or more and 100,000 mPa · s or less, more preferably 500 mPa · s or more and 20,000 mPa · s or less. Further, at a shear rate of 1000 S ⁻¹ , 1 mPa · s to 200 mPa · s is preferable, and 5 mPa · s to 80 mPa · s is more preferable.

In the case of preparing a coating liquid, a known in-line mixer or implant mixer is preferably used when mixing two kinds of liquids. A preferable in-line mixer in the present invention is described in JP-A No. 2002-85948, and an implant mixer is described in JP-A No. 2002-90940.
The coating solution in the present invention is preferably subjected to defoaming treatment in order to keep the coated surface state good. A preferable defoaming treatment method in the present invention is the method described in JP-A No. 2002-66431.
When applying the coating solution, it is preferable to perform static elimination in order to prevent adhesion of dust, dust, and the like due to electric resistance of the support. An example of a preferable static elimination method in the present invention is described in JP-A No. 2002-143747.
In the present invention, it is important to precisely control the drying air and the drying temperature in order to dry the non-setting image forming layer coating solution. Preferred drying methods in the present invention are described in detail in JP-A Nos. 2001-194749 and 2002-139814.
The photothermographic material of the present invention is preferably subjected to a heat treatment immediately after coating and drying in order to improve film formability. The temperature of the heat treatment is preferably in the range of 60 ° C. to 100 ° C. as the film surface temperature, and the heating time is preferably in the range of 1 second to 60 seconds. A more preferable range is such that the film surface temperature is 70 ° C. to 90 ° C. and the heating time is 2 seconds to 10 seconds. A preferable heat treatment method in the present invention is described in JP-A No. 2002-107872.
In order to stably and continuously produce the photothermographic material of the present invention, the production methods described in JP-A Nos. 2002-156728 and 2002-182333 are preferably used.

  The photothermographic material is preferably a mono-sheet type (a type capable of forming an image on the photothermographic material without using another sheet such as an image receiving material).

9) Packaging material The photothermographic material of the present invention is a packaging material having a low oxygen permeability and / or moisture permeability in order to suppress fluctuations in photographic performance during raw storage or to improve curling, curling, etc. It is preferable to package. The oxygen permeability is preferably 50 mL / atm · m ² · day or less at 25 ° C., more preferably 10 mL / atm · m ² · day or less, more preferably 1.0 mL / atm · m ² · day or less. is there. The moisture permeability is preferably 10 g / atm · m ² · day or less, more preferably 5 g / atm · m ² · day or less, and still more preferably 1 g / atm · m ² · day or less.
Specific examples of the packaging material having low oxygen permeability and / or moisture permeability are disclosed in, for example, JP-A-8-254793. This is a packaging material described in JP-A-2000-206653.

  In the present invention, the cutting process for cutting the sheet-shaped recording material into a predetermined size, and the packaging process for packaging the cut sheet-shaped recording material in the packaging material, the cleanliness is less than US Federal Standard 209d class 10,000. It is preferably performed in an environment. Further, if the packaging material is cleaned before the packaging process, the effect can be further exhibited.

  The degree of cleanliness in the cutting process is preferably a class 7,000 or less, more preferably 4,000 or less, even more preferably 1,000 or less, by a measuring method according to the US Federal Standard 209d, Particularly preferably, it is 500 or less. The degree of cleanliness in the packaging process is preferably a class 7,000 or less, more preferably 4,000 or less, even more preferably 1,000 or less, by a measurement method according to the US Federal Standard 209d, Particularly preferably, it is 500 or less.

  According to the present invention, the risk of causing image defects when image recording is performed on a sheet-like recording material by performing the cutting process and / or the packaging process in an environment of US Federal Standard 209d class 10,000 or less. Can be greatly reduced. Specifically, when image recording is performed on a sheet-like recording material, generation of white spots and scratches can be suppressed as much as possible.

  In the present invention, the packaging material used for packaging the sheet-like recording material is preferably selected from those that do not easily generate dust. In particular, it is preferable not to select such a packaging material when the dust derived from the packaging material makes it impossible to maintain an environment with a cleanness of US Federal Standard 209d class 10,000 or less.

10) Other technologies that can be used Techniques that can be used for the photothermographic material of the present invention include EP80364A1, EP883022A1, WO98 / 36322, JP-A-56-62648, JP-A-58-62644, and JP-A-5-62644. 9-43766, 9-281737, 9-297367, 9-304869, 9-31405, 9-329865, 10-10669, 10-62899, 10-69023 10-186568, 10-90823, 10-171603, 10-186565, 10-186567, 10-186567 to 10-186572, 10-197974, Nos. 10-197982, 10-197983, 10-197985 to 1 0-197987, 10-207001, 10-207004, 10-221807, 10-282601, 10-288823, 10-288824, 10-307365, 10- No. 312038, No. 10-339934, No. 11-7100, No. 11-15105, No. 11-24200, No. 11-24201, No. 11-30832, No. 11-84574, No. 11-65021 11-109547, 11-125880, 11-129629, 11-133536 to 11-133539, 11-133542, 11-133543, 11-223898, 11-352627, 11-305377, 11-305378, 11-305 84, 11-305380, 11-316435, 11-327076, 11-338096, 11-338098, 11-338099, 11-343420, 2001-200414 2001-234635, 2002-020699, 2001-275471, 2001-275461, 2000-313204, 2001-292844, 2000-324888, 2001-293864, 2001-348546 and 2000-187298 are also mentioned.

In the case of a multicolor color photothermographic material, each image-forming layer is generally functional or photosensitive between each photosensitive layer (image-forming layer) as described in US Pat. No. 4,460,681. By using a non-functional barrier layer, they are kept separate from each other.
The construction in the case of a multicolor color photothermographic material may comprise a combination of these two layers for each color and all within a single layer as described in US Pat. No. 4,708,928. Ingredients may be included.

3. Image Forming Method 1) Exposure Red to infrared emission He—Ne laser, red semiconductor laser, blue to green emission Ar ⁺ , He—Ne, He—Cd laser, blue semiconductor laser. Preferred is a red to infrared semiconductor laser, and the peak wavelength of the laser light is 600 nm to 900 nm, preferably 620 nm to 850 nm.
On the other hand, in recent years, in particular, a module in which an SHG (Second Harmonic Generator) element and a semiconductor laser are integrated and a blue semiconductor laser have been developed, and a laser output device in a short wavelength region has been closed up. The blue semiconductor laser is expected to increase in demand in the future because high-definition image recording is possible, the recording density is increased, and a stable output is obtained with a long lifetime. The peak wavelength of the blue laser light is preferably 300 nm to 500 nm, particularly preferably 400 nm to 500 nm.
It is also preferable that the laser light is oscillated in a vertical multi by a method such as high frequency superposition.

2) Thermal development Although the photothermographic material of the present invention may be developed by any method, it is usually developed by raising the temperature of the photothermographic material exposed imagewise. The development temperature is preferably 80 ° C. or higher and 250 ° C. or lower, preferably 100 ° C. or higher and 140 ° C. or lower, more preferably 110 ° C. or higher and 130 ° C. or lower. The development time is preferably 1 second to 60 seconds, more preferably 3 seconds to 30 seconds, still more preferably 5 seconds to 25 seconds, and particularly preferably 7 seconds to 16 seconds.
The photothermographic material of the present invention can be developed even when the conveyance speed during heat development is as high as 23 mm / sec or more. Even if it is a case where it is set as the composition of such a rapid processing photosensitive material, by having the layer structure concerning this invention, preservability becomes favorable. Furthermore, development is possible even at 27 mm / sec or more.

  Either a drum type heater or a plate type heater may be used as the thermal development method, but the plate type heater method is more preferable. The heat development method using the plate type heater method is preferably a method described in JP-A-11-133572, and a visible image is obtained by bringing a photothermographic material having a latent image formed thereon into contact with a heating means in a heat developing unit. In the heat development apparatus, the heating unit includes a plate heater, and a plurality of press rollers are disposed to face each other along one surface of the plate heater, and the press roller is disposed between the press roller and the plate heater. A heat development apparatus characterized in that heat development is performed by passing a photothermographic material. It is preferable to divide the plate heater into 2 to 6 stages and lower the temperature about 1 ° C. to 10 ° C. at the tip. For example, an example in which four sets of plate heaters capable of independent temperature control are used and the temperature is controlled to 112 ° C., 119 ° C., 121 ° C., and 120 ° C., respectively. Such a method is also described in JP-A-54-30032, which can exclude moisture and organic solvents contained in the photothermographic material out of the system, and rapidly develop the photothermographic material. It is also possible to suppress a change in the shape of the support of the photothermographic material due to the heating.

  In order to reduce the size of the heat developing machine and shorten the heat development time, it is preferable that more stable heater control can be performed. Imagers capable of rapid processing preferable for the present invention are described in, for example, JP-A Nos. 2002-289804 and 091114. If this imager is used, for example, heat development can be performed in 14 seconds with a three-stage plate heater controlled at 107 ° C.-121 ° C.-121 ° C., and the output time of the first sheet is reduced to about 60 seconds. be able to. For such rapid development processing, it is preferable to use the photothermographic material-2 of the present invention in combination with high sensitivity and less susceptible to environmental temperature.

When the distance between the exposure part and the development part becomes short, a series of processing time for exposure and development becomes extremely short. Moreover, since the heat developing machine can be made compact, the distance is preferably short. If the photothermographic material of the present invention is used, an image having no unevenness can be obtained even when the distance between the exposed portion and the developing portion is from 0 cm to 50 cm, and the obtained image has good storage stability. is there. Furthermore, even if this distance is 3 cm or more and 40 cm or less, the effect of the present invention can be obtained.
Here, the exposure part refers to a position where light from an exposure light source is irradiated to the photothermographic material, and the development part refers to a position where the photothermographic material is heated for the first time for heat development. In FIG. 2, X is an exposure unit, and Y is the developing unit where the photosensitive material conveyed from 53 in FIG. 1 is first in contact with the plate 51a. Even in a developing machine having this distance of 50 cm or less, the effects of the invention can be obtained by using the photothermographic material according to the invention.

  In particular, even when a part of the sheet-sensitive material is exposed and development is started on a part of the sheet that has already been exposed, by using the photothermographic material of the present invention, the exposed portion is contaminated by the volatile substance. This problem is solved. In addition, this method can further shorten the processing time.

When the power supply of the heat development apparatus is turned off overnight, the heat development unit is at the same temperature as the room temperature. Immediately after the power is turned on, it is difficult to obtain a stable output image, for example, because the preferred development temperature has not been reached or the hunting width of the temperature is large. Therefore, it takes time to raise the temperature of the thermal development section and to stabilize it in order to achieve the above-mentioned preferable development conditions.
Since the photothermographic material of the present invention is not easily affected by the external environment and the image output is stable, a stable image can be obtained even under severe development conditions in which development is started in a short time after the power is turned on. It is done.

  For example, the storage stability of the obtained image is good even if the time from when the power of the heat development apparatus is turned on until the leading edge of the photothermographic material reaches the heat development portion is within 15 minutes. Here, the “tip of the photothermographic material” refers to a part of the photosensitive material that reaches the warmed portion of the heat developing device earliest when the photosensitive material made of the photothermographic material is conveyed after exposure. “Thermal development part” refers to the heated part of the thermal developing machine.

3) System As a medical laser imager provided with an exposure part and a heat development part, Fuji Medical Dry Laser Imager FM-DPL and DRYPIX7000 can be exemplified. Regarding FM-DPL, Fuji Medical Review No. 8, pages 39 to 55, and it goes without saying that those techniques are applied as a laser imager of the photothermographic material of the present invention. Further, it can also be applied as a photothermographic material for a laser imager in “AD network” proposed by Fuji Film Medical Co., Ltd. as a network system adapted to the DICOM standard.

4). Use of the Invention The photothermographic material of the invention forms a black-and-white image by a silver image, and is used for medical diagnosis, photothermographic material for industrial photography, photothermographic material for printing, heat for COM. It is preferably used as a developing photosensitive material.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Example 1
(Preparation of PET support)
1) Film formation Using terephthalic acid and ethylene glycol, PET having an intrinsic viscosity of IV = 0.66 (measured in phenol / tetrachloroethane = 6/4 (mass ratio) at 25 ° C.) is obtained. It was. This was pelletized, dried at 130 ° C. for 4 hours, melted at 300 ° C., extruded from a T-die, and rapidly cooled to prepare an unstretched film.

This was stretched 3.3 times longitudinally using rolls with different peripheral speeds, and then stretched 4.5 times with a tenter. The temperatures at this time were 110 ° C. and 130 ° C., respectively. Thereafter, after heat setting at 240 ° C. for 20 seconds, the film was relaxed by 4% in the lateral direction at the same temperature. Thereafter, the chuck portion of the tenter was slit and then knurled at both ends, and wound at 4 kg / cm ² to obtain a roll having a thickness of 175 μm.

2) Surface corona discharge treatment Using a solid state corona discharge treatment machine 6KVA model manufactured by Pillar, both surfaces of the support were treated at room temperature at 20 m / min. From the current and voltage readings at this time, it was found that the support was processed at 0.375 kV · A · min / m ² . The treatment frequency at this time was 9.6 kHz, and the gap clearance between the electrode and the dielectric roll was 1.6 mm.

3) Undercoat formulation (1) (for the undercoat layer on the image forming layer side)
・ Pesresin A-520 (30% by mass solution) manufactured by Takamatsu Yushi Co., Ltd. 46.8 g
・ Toyobo Co., Ltd. Bironal MD-1200 10.4 g
Polyethylene glycol monononyl phenyl ether (average ethylene oxide number = 8.5) 1% by weight solution 11.0 g
・ MP-1000 (PMMA polymer fine particles, average particle size 0.4 μm) manufactured by Soken Chemical Co., Ltd.
0.91g
・ Distilled water 931mL

Formula (2) (for back layer 1st layer)
・ Styrene-butadiene copolymer latex 130.8 g
(Solid content 40% by mass, styrene / butadiene mass ratio = 68/32)
2,4-dichloro-6-hydroxy-S-triazine sodium salt (8% by mass aqueous solution)
5.2g
・ 10 mL of 1% by weight aqueous solution of sodium laurylbenzenesulfonate
・ Polystyrene particle dispersion (average particle size 2 μm, 20 mass%) 0.5 g
-854 mL of distilled water

Formula (3) (for back side second layer)
SnO ₂ / SbO (9/1 mass ratio, average particle size 0.5 μm, 17 mass% dispersion) 84 g
・ Gelatin 7.9g
・ Shin-Etsu Chemical Co., Ltd. Metros TC-5 (2 mass% aqueous solution) 10g
・ 10% 1% aqueous solution of sodium dodecylbenzenesulfonate
・ NaOH (1% by mass) 7 g
・ Proxel (Abyssia) 0.5g
・ 881mL distilled water

After both surfaces of the biaxially stretched polyethylene terephthalate support having a thickness of 175 μm are subjected to the corona discharge treatment, the undercoat coating solution formulation (1) is applied on one side (image forming layer surface) with a wire bar with a wet coating amount of 6. .6mL / m ² was applied (per one side) and dried for 5 minutes at 180 ° C., then the amount of wet coating the coating solution for the undercoat was coated (2) by a wire bar on the rear surface (back surface) 5. was applied so as to 7 mL / m ² and dried 5 minutes at 180 ° C., wet coating amount is 8.4 mL / m ² further back surface (the back surface) the coating solution for the undercoat was coated (3) with a wire bar It was applied as described above and dried at 180 ° C. for 6 minutes to prepare an undercoat support.

(Back layer)
1) Preparation of back layer coating solution (preparation of solid fine particle dispersion (a) of base precursor)
Add 2.5 kg of base precursor compound 1 and 300 g of a surfactant (trade name: Demol N, manufactured by Kao Corporation), 800 g of diphenylsulfone, 1.0 g of benzoisothiazolinone sodium salt and distilled water to make a total amount. The mixture was mixed to 8.0 kg, and the mixed solution was dispersed with beads using a horizontal sand mill (UVM-2: manufactured by Imex Corporation). In the dispersion method, the mixed solution was fed to UVM-2 filled with zirconia beads having an average diameter of 0.5 mm by a diaphragm pump, and dispersed in a state where the internal pressure was 50 hPa or more until a desired average particle size was obtained.
The dispersion was subjected to spectral absorption measurement, and the ratio of the absorbance at 450 nm to the absorbance at 650 nm (D ₄₅₀ / D ₆₅₀ ) in the spectral absorption of the dispersion was dispersed to 3.0. The obtained dispersion was diluted with distilled water so that the concentration of the base precursor was 25% by mass, and was filtered for removal of dust (polypropylene filter having an average pore size of 3 μm) for practical use.

2) Preparation of Dye Solid Fine Particle Dispersion 6.0 kg of cyanine dye compound-1 and 3.0 kg of sodium p-dodecylbenzenesulfonate, 0.6 kg of surfactant Demol SNB manufactured by Kao Corporation, and antifoaming agent (trade name) : Surfynol 104E, manufactured by Nissin Chemical Co., Ltd.) 0.15 kg was mixed with distilled water to make a total liquid volume of 60 kg. The mixed solution was dispersed with 0.5 mm zirconia beads using a horizontal sand mill (UVM-2: manufactured by Imex Corporation).
The dispersion was dispersed until the ratio of the absorbance at 650 nm to the absorbance at 750 nm (D ₆₅₀ / D ₇₅₀ ) in the spectral absorption of the dispersion was 5.0 or more. The obtained dispersion was diluted with distilled water so that the concentration of the cyanine dye was 6% by mass, and was subjected to filter filtration (average pore diameter: 1 μm) for dust removal, and was put to practical use.

3) Preparation of antihalation layer coating solution The container was kept at 40 ° C., and 40 g of gelatin, 0.1 g of benzoisothiazolinone and 490 mL of water were added to dissolve the gelatin. Further, 2.3 mL of a 1 mol / L sodium hydroxide aqueous solution, 40 g of the dye solid fine particle dispersion, 90 g of the solid fine particle dispersion (a) of the base precursor, 12 mL of a 3% by weight aqueous solution of sodium polystyrenesulfonate, 10% by weight of SBR latex 180 g of the liquid was mixed. Immediately before coating, 80 mL of a 4% by weight aqueous solution of N, N-ethylenebis (vinylsulfone acetamide) was mixed to prepare an antihalation layer coating solution.

4) Preparation of back surface protective layer coating solution << Preparation of back surface protective layer coating solution-1 >>
The container was kept at 40 ° C., and 40 g of gelatin, 35 mg of benzoisothiazolinone, and 840 mL of water were added to dissolve the gelatin. Further, 5.8 mL of a 1 mol / L sodium hydroxide aqueous solution, 5 g of a 10% by weight emulsion of liquid paraffin, 5 g of a 10% by weight emulsion of trimethylolpropane triisostearate, di (2-ethylhexyl) sodium sulfosuccinate 5 10% by weight aqueous solution, 20 ml of 3% by weight polystyrene sodium sulfonate aqueous solution, 2.4% by weight of 2% by weight of fluorosurfactant (FF-1), and 2% by weight of 2% by weight of fluorosurfactant (FF-2) .4mL, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio 57/8/28/5/2) Latex 19% liquid 32g was mixed. Just before coating, 25 mL of a 4% by weight aqueous solution of N, N-ethylenebis (vinylsulfone acetamide) was mixed to prepare a coating solution for the back surface protective layer.

4) Application of back layer On the back surface side of the undercoat support, an antihalation layer coating solution was applied to a gelatin coating amount of 0.52 g / m ^2, and a back surface protective layer coating solution was applied to a gelatin coating amount of 1. A simultaneous multilayer coating was applied so as to be 0.7 g / m ² , followed by drying to prepare a back layer.

(Image forming layer, intermediate layer, and surface protective layer)
1. Preparation of coating materials 1) Silver halide emulsion << Preparation of silver halide emulsion 1 >>
To a solution of 1421 mL of distilled water, 3.1 mL of a 1% by mass potassium bromide solution was added, and a solution containing 3.5 mL of 0.5 mol / L sulfuric acid and 31.7 g of phthalated gelatin was stirred in a stainless steel reaction vessel. While maintaining the liquid temperature at 30 ° C., the solution A diluted with 92.2 mL of distilled water added to 22.22 g of silver nitrate, 15.3 g of potassium bromide and 0.8 g of potassium iodide in a distilled water volume of 97.4 mL The whole amount of the solution B diluted to 1 was added at a constant flow rate over 45 seconds. Thereafter, 10 mL of a 3.5% by mass aqueous hydrogen peroxide solution was added, and further 10.8 mL of a 10% by mass aqueous solution of benzimidazole was added. Further, a solution C in which distilled water was added to 51.86 g of silver nitrate and diluted to 317.5 mL, a solution D in which 44.2 g of potassium bromide and 2.2 g of potassium iodide were diluted with distilled water to a volume of 400 mL were added to solution C. Was added at a constant flow rate over 20 minutes, and solution D was added by the controlled double jet method while maintaining pAg at 8.1. The total amount of potassium hexachloroiridium (III) was added 10 minutes after the start of the addition of the solution C and the solution D so as to be 1 × 10 ⁻⁴ mol per mol of silver. Further, 5 seconds after the completion of the addition of the solution C, an aqueous solution of potassium iron (II) hexacyanide was added in an amount of 3 × 10 ⁻⁴ mol per mol of silver. The pH was adjusted to 3.8 using sulfuric acid having a concentration of 0.5 mol / L, stirring was stopped, and a precipitation / desalting / water washing step was performed. The pH was adjusted to 5.9 with 1 mol / L sodium hydroxide to prepare a silver halide dispersion having a pAg of 8.0.

The silver halide dispersion was maintained at 38 ° C. with stirring, 5 mL of a 0.34 mass% 1,2-benzisothiazolin-3-one methanol solution was added, and the temperature was raised to 47 ° C. after 40 minutes. 20 minutes after the temperature increase, sodium benzenethiosulfonate was added in a methanol solution to 7.6 × 10 ⁻⁵ moles per 1 mole of silver, and 5 minutes later, tellurium sensitizer C was added in a methanol solution at a rate of 2. per mol of silver. 9 × 10 ⁻⁴ mol was added and aged for 91 minutes. Thereafter, a methanol solution having a molar ratio of the spectral sensitizing dye A and the sensitizing dye B of 3: 1 was added in an amount of 1.2 × 10 ⁻³ mol as a total of the sensitizing dyes A and B per mol of silver. , N′-dihydroxy-N ″ -diethylmelamine in 1.3 mL of a 0.8 wt% methanol solution was added, and after an additional 4 minutes, 5-methyl-2-mercaptobenzimidazole was added to the methanol solution at a rate of 4.8 per mole of silver. × 10 ⁻³ mol, 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole in methanol solution to 5.4 × 10 ⁻³ mol and 1- (3-methyl) with respect to 1 mol of silver A silver halide emulsion 1 was prepared by adding 8.5 × 10 ⁻³ mol of ureidophenyl) -5-mercaptotetrazole in an aqueous solution to 1 mol of silver.

  The grains in the prepared silver halide emulsion were silver iodobromide grains containing 3.5 mol% of iodine having an average sphere equivalent diameter of 0.042 μm and a sphere equivalent diameter variation coefficient of 20%. The particle size and the like were determined from an average of 1000 particles using an electron microscope. The {100} face ratio of the particles was determined to be 80% using the Kubelka-Munk method.

<< Preparation of silver halide emulsion 2 >>
In the preparation of silver halide emulsion 1, the liquid temperature 30 ° C. at the time of grain formation was changed to 47 ° C., and solution B was changed to diluting 15.9 g of potassium bromide to a volume of 97.4 mL with distilled water, Solution D was changed to diluting 45.8 g of potassium bromide with distilled water to a volume of 400 mL, and the addition time of solution C was changed to 30 minutes to remove potassium hexacyanoiron (II) in the same manner. Further, precipitation / desalting / washing / dispersion was carried out in the same manner as in the case of the silver halide emulsion 1 to obtain a silver halide dispersion 2. Furthermore, the amount of tellurium sensitizer C added to the silver halide dispersion 2 was 1.1 × 10 ⁻⁴ mol per mol of silver, and the molar ratio of spectral sensitizing dye A and spectral sensitizing dye B was 3: 1. The total amount of sensitizing dye A and sensitizing dye B per mole of silver is 7.0 × 10 ⁻⁴ mol, 1-phenyl-2-heptyl-5-mercapto-1,3,4 Triazole was changed to 3.3 × 10 ⁻³ mol per mol of silver and 1- (3-methylureidophenyl) -5-mercaptotetrazole was added to 4.7 × 10 ⁻³ mol per mol of silver. Except for Emulsion 1, spectral sensitization, chemical sensitization and addition of 5-methyl-2-mercaptobenzimidazole, 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole were performed, A silver halide emulsion 2 was obtained. The emulsion grains of silver halide emulsion 2 were pure silver bromide cubic grains having an average sphere equivalent diameter of 0.080 μm and a sphere equivalent diameter variation coefficient of 20%.

<< Preparation of silver halide emulsion 3 >>
Preparation of silver halide emulsion 1 was carried out in the same manner except that the liquid temperature at the time of grain formation was changed from 30 ° C. to 27 ° C., and precipitation / desalting / water washing / dispersion was carried out in the same manner as the preparation of silver halide dispersion 1. And a silver halide dispersion 3 was obtained. Into the silver halide dispersion 3, the molar ratio of the spectral sensitizing dye A and the spectral sensitizing dye B is 1: 1 as a solid dispersion (gelatin aqueous solution), and the addition amount is the sensitizing dye A and the sensitizing dye per mole of silver. The total amount of B was changed to 6 × 10 ⁻³ mol, and the addition amount of tellurium sensitizer C was changed to 5.2 × 10 ⁻⁴ mol per mol of silver. A silver halide emulsion 3 was obtained in the same manner as Emulsion 1 except that 5 × 10 ⁻⁴ mol per mol and 2 × 10 ⁻³ mol of potassium thiocyanate per mol of silver were added. The emulsion grains of the silver halide emulsion 3 were silver iodobromide grains containing 3.5 mol% of iodine having an average sphere equivalent diameter of 0.034 μm and a sphere equivalent diameter variation coefficient of 20%.

<< Preparation of mixed emulsion A for coating solution >>
70% by weight of silver halide emulsion 1, 15% by weight of silver halide emulsion 2 and 15% by weight of silver halide emulsion 3 were dissolved, and benzothiazolium iodide was dissolved in a 1% by weight aqueous solution of 7% per mole of silver. × 10 ⁻³ mol was added.
Further, the amount of the one-electron oxidant produced by one-electron oxidation is 2 × 10 ⁻³ moles per mole of silver halide, each of compounds 1, 2, and 3 capable of emitting one electron or more. Added.
Adsorbing redox compounds 1 and 2 having an adsorbing group and a reducing group were added in an amount of 5 × 10 ⁻³ mol per mol of silver halide.
Further, water was added so that the content of silver halide per 1 kg of the mixed emulsion for coating solution was 38.2 g as silver. 1- (3-Methylureidophenyl) -5-mercaptotetrazole was added so as to be 0.34 g per kg of the mixed emulsion for coating solution.

2) Preparation of organic silver salt dispersion <Purification of recrystallized behenic acid A>
100 kg of behenic acid (product name Edenor C22-85R) manufactured by Henkel was mixed in 1200 kg of isopropyl alcohol, dissolved at 50 ° C., filtered through a 10 μm filter, cooled to 30 ° C., and recrystallized. The cooling speed during recrystallization was controlled at 3 ° C./hour. The obtained crystals were centrifugally filtered, washed with 100 kg of isopropyl alcohol, and then recrystallized twice more. Thereafter, the precipitate at the initial stage of recrystallization was filtered to remove lignoceric acid and dried. The obtained crystals were esterified and subjected to GC-FID measurement. As a result, the behenic acid content was 99.99 mol%. In addition, erucic acid was 0.000001 mol% or less.

<Purification of recrystallized stearic acid>
100 kg of stearic acid manufactured by Tokyo Chemical Industry was mixed in 1200 kg of isopropyl alcohol, dissolved at 50 ° C., filtered through a 10 μm filter, cooled to 20 ° C., and recrystallized. The cooling speed during recrystallization was controlled at 3 ° C./hour. The obtained crystals were centrifugally filtered, washed with 100 kg of isopropyl alcohol, and then recrystallized twice more. Thereafter, the precipitate at the initial stage of recrystallization was filtered to remove carboxylic acid having a chain length longer than that of stearic acid, followed by drying. When the obtained crystals were esterified and subjected to GC-FID measurement, the stearic acid content was 99.99 mol%. In addition, erucic acid was 0.000001 mol% or less.

(Preparation of organic silver salt dispersion A)
40 g of recrystallized behenic acid A, 7.3 g of recrystallized stearic acid, and 500 mL of water are stirred at a temperature of 90 ° C. for 15 minutes, 187 mL of 1N NaOH is added over 15 minutes, and 61 mL of 1N nitric acid aqueous solution is added to 50 ° C. The temperature dropped. Next, 124 mL of a 1N silver nitrate aqueous solution was added over 2 minutes, and the mixture was stirred as it was for 30 minutes. Thereafter, the solid content was separated by suction filtration, and the solid content was washed with water until the filtrate had a conductivity of 30 μS / cm. The solid content thus obtained was stored as a wet cake without drying.
The obtained crystals had a behenic acid content of 82 mol% and stearic acid 18 mol%.

  19.3 kg of polyvinyl alcohol (trade name: PVA-217) and water are added to a wet cake corresponding to a dry solid content of 260 kg to make a total amount of 1000 kg, and then slurried with a dissolver blade, and a pipeline mixer (manufactured by Mizuho Kogyo Co., Ltd.) : PM-10 type).

Next, the pre-dispersed undiluted solution is adjusted to a pressure of 1150 kg / cm ² in a disperser (trade name: Microfluidizer M-610, manufactured by Microfluidics International Corporation, using a Z-type interaction chamber) three times. Treatment gave a silver behenate dispersion. The cooling operation was set to a dispersion temperature of 18 ° C. by installing a serpentine heat exchanger before and after the interaction chamber and adjusting the temperature of the refrigerant.
Preparation of organic silver salt dispersion A, which is needle-like particles having an average minor axis of 0.04 μm, an average major axis of 0.8 μm, and a projected area variation coefficient of 30%, was completed by electron microscope observation.

3) Preparation of reducing agent dispersion << Preparation of reducing agent-1 dispersion >>
10 mass of reducing agent-1 (6,6′-di-t-butyl-4,4′-dimethyl-2,2′-butylidenediphenol) and modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) 10 kg of water was added to 16 kg of% aqueous solution and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump and dispersed for 3 hours 30 minutes in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm, and then benzoisothiazolinone sodium salt 0.2 g and water were added to prepare a reducing agent concentration of 25% by mass. This dispersion was heated at 40 ° C. for 1 hour, and then further heated at 80 ° C. for 1 hour to obtain a reducing agent-1 dispersion. The reducing agent particles contained in the reducing agent dispersion thus obtained had a median diameter of 0.50 μm and a maximum particle diameter of 1.6 μm or less. The obtained reducing agent dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

4) Preparation of Hydrogen Bonding Compound-1 Dispersion 10 kg of hydrogen bonding compound-1 (tri (4-t-butylphenyl) phosphine oxide) and modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) 10 kg of water was added to 16 kg of the aqueous solution and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump, and dispersed for 4 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm. 2 g and water were added to prepare a hydrogen bonding compound concentration of 25% by mass. This dispersion was heated at 40 ° C. for 1 hour and then further heated at 80 ° C. for 1 hour to obtain a hydrogen bonding compound-1 dispersion. The hydrogen bonding compound particles contained in the hydrogen bonding compound dispersion thus obtained had a median diameter of 0.45 μm and a maximum particle diameter of 1.3 μm or less. The obtained hydrogen bonding compound dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

5) Preparation of Development Accelerator-1 Dispersion 10 kg of Development Accelerator-1 and 20 kg of 10% by weight aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) were added with 10 kg of water and mixed well. To make a slurry. This slurry was fed with a diaphragm pump and dispersed for 3 hours 30 minutes in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm, and then benzoisothiazolinone sodium salt 0.2 g and water were added to adjust the concentration of the development accelerator to 20% by mass to obtain a development accelerator-1 dispersion. The development accelerator particles contained in the development accelerator dispersion thus obtained had a median diameter of 0.48 μm and a maximum particle diameter of 1.4 μm or less. The obtained development accelerator dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

6) Preparation of Dispersion of Development Accelerator-2 and Color Adjuster-1 The solid dispersion of Development Accelerator-2 and Color Adjuster-1 was also dispersed by the same method as Development Accelerator-1, each having 20 mass. % And 15% by mass dispersion liquid were obtained.

7) Preparation of polyhalogen compound << Preparation of organic polyhalogen compound-1 dispersion >>
10 kg of organic polyhalogen compound-1 (tribromomethanesulfonylbenzene), 10 kg of 20 wt% aqueous solution of modified polyvinyl alcohol (Poval MP203 manufactured by Kuraray Co., Ltd.), 0.4 kg of 20 wt% aqueous solution of sodium triisopropylnaphthalenesulfonate, Then, 14 kg of water was added and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump and dispersed for 5 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm. 2 g and water were added to prepare an organic polyhalogen compound concentration of 26% by mass to obtain an organic polyhalogen compound-1 dispersion. The organic polyhalogen compound particles contained in the polyhalogen compound dispersion thus obtained had a median diameter of 0.41 μm and a maximum particle diameter of 2.0 μm or less. The obtained organic polyhalogen compound dispersion was filtered through a polypropylene filter having a pore size of 10.0 μm to remove foreign substances such as dust and stored.

<< Preparation of organic polyhalogen compound-2 dispersion >>
10 kg of an organic polyhalogen compound-2 (N-butyl-3-tribromomethanesulfonylbenzoamide), 20 kg of a 10% by weight aqueous solution of modified polyvinyl alcohol (Poval MP203 manufactured by Kuraray Co., Ltd.), and 20 of sodium triisopropylnaphthalenesulfonate 0.4 kg of a mass% aqueous solution was added and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump and dispersed for 5 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm. 2 g and water were added to prepare an organic polyhalogen compound concentration of 30% by mass. This dispersion was heated at 40 ° C. for 5 hours to obtain an organic polyhalogen compound-2 dispersion. The organic polyhalogen compound particles contained in the polyhalogen compound dispersion thus obtained had a median diameter of 0.40 μm and a maximum particle diameter of 1.3 μm or less. The obtained organic polyhalogen compound dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

8) Preparation of phthalazine compound-1 solution 8 kg of modified polyvinyl alcohol MP203 manufactured by Kuraray Co., Ltd. was dissolved in 174.57 kg of water, and then 3.15 kg of a 20 mass% aqueous solution of sodium triisopropylnaphthalenesulfonate and phthalazine compound-1 ( 14.28 kg of a 70% by weight aqueous solution of 6-isopropylphthalazine) was added to prepare a 5% by weight solution of phthalazine compound-1.

9) Preparation of mercapto compound << Preparation of aqueous solution of mercapto compound-1 >>
7 g of mercapto compound-1 (1- (3-sulfophenyl) -5-mercaptotetrazole sodium salt) was dissolved in 993 g of water to obtain a 0.7% by mass aqueous solution.

<< Preparation of Mercapto Compound-2 Aqueous Solution >>
20 g of mercapto compound-2 (1- (3-methylureidophenyl) -5-mercaptotetrazole) was dissolved in 980 g of water to obtain a 2.0 mass% aqueous solution.

10) Preparation of Pigment-1 Dispersion C.I. I. Pigment Blue 60 (64 g) and Kao Corp. Demol N (6.4 g) were added to 250 g of water and mixed well to obtain a slurry. Prepare 800 g of zirconia beads having an average diameter of 0.5 mm, put them in a vessel together with the slurry, and disperse with a disperser (1/4 G sand grinder mill: manufactured by IMEX Co., Ltd.) for 25 hours. A pigment-1 dispersion was obtained by adjusting the concentration to 5% by mass. The pigment particles contained in the pigment dispersion thus obtained had an average particle size of 0.21 μm.

11) Preparation of SBR latex solution SBR latex was prepared as follows.
In a polymerization kettle of a gas monomer reactor (TAS-2J type manufactured by Pressure Glass Industrial Co., Ltd.), 287 g of distilled water and a surfactant (Pionin A-43-S (manufactured by Takemoto Yushi Co., Ltd.)): solid content 48.5 (Mass%) 7.73 g, 1 mol / L, NaOH 14.06 mL, ethylenediaminetetraacetic acid tetrasodium salt 0.15 g, styrene 255 g, acrylic acid 11.25 g, tert-dodecyl mercaptan 3.0 g were put, and the reaction vessel was sealed and stirred. Stir at a speed of 200 rpm. After degassing with a vacuum pump and repeating nitrogen gas replacement several times, 108.75 g of 1,3-butadiene was injected and the internal temperature was raised to 60 ° C. A solution prepared by dissolving 1.875 g of ammonium persulfate in 50 mL of water was added thereto and stirred as it was for 5 hours. The temperature was further raised to 90 ° C., and the mixture was stirred for 3 hours. After completion of the reaction, the internal temperature was lowered to room temperature, and then Na ⁺ ion: NH ₄ ⁺ ion = 1: 1 using 1 mol / L NaOH and NH ₄ OH. Addition treatment was performed so that the molar ratio was 5.3 (molar ratio), and the pH was adjusted to 8.4. Thereafter, the mixture was filtered through a polypropylene filter having a pore size of 1.0 μm to remove foreign substances such as dust and stored, and 774.7 g of SBR latex was obtained. When halogen ions were measured by ion chromatography, the chloride ion concentration was 3 ppm. The concentration of the chelating agent measured by high performance liquid chromatography was 145 ppm.

  The latex has an average particle size of 90 nm, Tg = 17 ° C., solid content concentration of 44 mass%, equilibrium moisture content at 25 ° C. and 60% RH, 0.6 mass%, ion conductivity of 4.80 mS / cm (measurement of ion conductivity is A latex stock solution (44 mass%) was measured at 25 ° C. using a conductivity meter CM-30S manufactured by Toa Denpa Kogyo Co., Ltd.).

2. Preparation of coating solution 1) Preparation of image forming layer coating solution-1 1000 g of fatty acid silver dispersion A obtained above, 135 mL of water, 36 g of pigment-1 dispersion, 25 g of organic polyhalogen compound-1 dispersion, organic polyhalogen compound- 2. Dispersion 39 g, phthalazine compound-1 solution 171 g, SBR latex (Tg: 17 ° C.) liquid 1060 g, reducing agent-1 dispersion 153 g, hydrogen bonding compound-1 dispersion 55 g, development accelerator-1 dispersion 8 g, 5.2 g of Development Accelerator-2 Dispersion, 2.1 g of Color Tone Modifier-1 Dispersion, 8 mL of Mercapto Compound-2 Aqueous Solution are added sequentially, and 140 g of Silver Halide Mixed Emulsion A 140 g is added and mixed well immediately before coating. The applied image forming layer coating solution was fed as it was to the coating die and applied.
The viscosity of the image forming layer coating solution was 40 [mPa · s] at 40 ° C. (No. 1 rotor, 60 rpm) as measured with a B-type viscometer of Tokyo Keiki.
The viscosity of the coating solution at 38 ° C. using a Haake RheoStress RS150 is 30, 43, 41, 28, 20 [mPa · s] at shear rates of 0.1, 1, 10, 100, 1000 [1 / second], respectively. s].
The amount of zirconium in the coating solution was 0.30 mg per 1 g of silver.

2) Preparation of intermediate layer A coating solution << Preparation of intermediate layer A coating solution-1 >>
Polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.) 1000 g, pigment-1 dispersion 163 g, blue dye compound-1 (manufactured by Nippon Kayaku Co., Ltd .: Kayafect Turquoise RN Liquid 150) 18.5 mass% aqueous solution 33 g, 27 mL of 5% by weight aqueous solution of di (2-ethylhexyl) sodium salt of sulfosuccinate, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio 57/8/28/5/2) Latex 19 Water was added to 4200 mL of a mass% liquid so that 27 mL of a 5 mass% aqueous solution of Aerosol OT (manufactured by American Cyanamid Co., Ltd.), 135 mL of a 20 mass% aqueous solution of diammonium phthalate salt, and a total amount of 10000 g were added. .5 Apply NaOH to adjust to 5 And then it was fed to a coating die to provide 8.9 mL / m ^2.
The viscosity of the coating solution was 58 [mPa · s] at 40 ° C. (No. 1 rotor, 60 rpm) B-type viscometer.

<< Preparation of Intermediate Layer A Coating Liquids 2-5 >>
In the preparation of the intermediate layer A coating liquid-1, the place where polyvinyl alcohol PVA-205 and methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer were used was changed to the binder shown in Table 2. Intermediate layer A coating liquids 2 to 5 were prepared.

3) Preparation of intermediate layer B coating solution << Preparation of intermediate layer B coating solution-1 >>
100 g of inert gelatin and 10 mg of benzoisothiazolinone are dissolved in 840 mL of water, and a methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio 57/8/28/5/2) latex 19 180% by weight liquid, 46 ml of 15% by weight methanol solution of phthalic acid, and 5.4 ml of 5% by weight aqueous solution of di (2-ethylhexyl) sulfosuccinate sodium salt were added and mixed, and 4% by weight chromium alum just before coating. A mixture of 40 mL with a static mixer was fed to the coating die so that the amount of the coating solution was 26.1 mL / m ² .
The viscosity of the coating solution was 20 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

<< Preparation of Intermediate Layer B Coating Liquids 2-5 >>
In the preparation of the intermediate layer B coating solution-1, the place where inert gelatin and methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer were used was changed to the binder shown in Table 2, and the intermediate layer B was changed. Coating liquids 2 to 5 were prepared.

4) Preparation of outermost layer coating solution << Preparation of outermost layer coating solution-1 >>
100 g of inert gelatin and 10 mg of benzoisothiazolinone are dissolved in 800 mL of water, 40 g of a 10% by weight emulsion of liquid paraffin, 40 g of a 10% by weight emulsion of dipentaerythrityl hexaisostearate, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl Methacrylate / acrylic acid copolymer (copolymerization mass ratio 57/8/28/5/2) Latex 19% by weight solution 180g, phthalic acid 15% by weight methanol solution 40mL, fluorosurfactant (FF-1) 1 5.5 mL of mass% solution, 5.5 mL of 1 mass% aqueous solution of fluorosurfactant (FF-2), 28 mL of 5 mass% aqueous solution of di (2-ethylhexyl) sodium sulfosuccinate, polymethyl methacrylate fine particles (Average particle size 0.7μm, volume weighted average Distribution 30%) 4g, polymethyl methacrylate fine particles (mean particle size 3.6 [mu] m, a mixture of distribution 60%) 21g of the volume weighted average surface protective layer coating solution, coating so that 8.3 mL / m ² Liquid was fed to the die.
The viscosity of the coating solution was 19 [mPa · s] at 40 ° C. (No. 1 rotor, 60 rpm) B-type viscometer.

<< Preparation of Outermost Layer Coating Solution-2-5 >>
In the preparation of the outermost layer coating solution-1, inert gelatin, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio 57/8/28/5/2) latex was used. Was changed to the binder shown in Table 2 to prepare outermost layer coating liquids 2 to 5.

3. Production of photothermographic material 1) Production of photothermographic material-1 Image forming layer coating solution-1, intermediate layer A coating solution-1, intermediate layer B coating solution-1 from the undercoat surface on the opposite side of the back surface, Samples of the photothermographic material were prepared by simultaneous multilayer coating in the order of the outermost layer coating solution by the slide bead coating method. At this time, the image forming layer and the intermediate layer coating solution were adjusted to 31 ° C., the surface protective layer first layer coating solution was adjusted to 36 ° C., and the surface protective layer second layer coating solution was adjusted to 37 ° C.
The coating amount (g / m ² ) of each compound in the image forming layer at this time is as follows.

Organic silver salt 4.878
Pigment (CI Pigment Blue 60) 0.0324
Polyhalogen compound-1 0.108
Polyhalogen compound-2 0.225
Phthalazine Compound-1 0.161
SBR latex 8.73
Reducing agent-1 0.77
Hydrogen bonding compound-1 0.522
Development accelerator-2 0.018
Mercapto Compound-1 0.0018
Mercapto compound-2 0.0108
Silver halide (as Ag) 0.09

The total coated silver amount of the photothermographic material-1 was 1.18 g / m ² .

The coating and drying conditions are as follows.
Application was performed at a speed of 160 m / min, the gap between the coating die tip and the support was set to 0.10 mm to 0.30 mm, and the pressure in the decompression chamber was set to be 196 to 882 Pa lower than the atmospheric pressure. The support was neutralized with an ion wind before coating.
In the subsequent chilling zone, the coating liquid is cooled with a wind at a dry bulb temperature of 10 ° C. to 20 ° C., then transported in a non-contact manner, and dried at a dry bulb temperature of 23 ° C. to 45 ° C. It dried with the drying wind of 15 degreeC and the wet-bulb temperature of 15 to 21 degreeC.
After drying, the humidity was adjusted at 25 ° C. and humidity of 40% RH to 60% RH, and then the film surface was heated to 70 ° C. to 90 ° C. After heating, the film surface was cooled to 25 ° C.

2) Preparation of photothermographic material-2 to 15 Photothermographic photosensitivity except that the image forming layer coating solution, the intermediate layer A coating solution, the intermediate layer B coating solution and the outermost layer coating solution were applied in the combinations shown in Table 2. Photothermographic materials -2 to 5 were prepared in the same manner as in the preparation of Material-1. Further, the intermediate layer B was divided into two to obtain photothermographic materials-6 to 15 having the compositions shown in Table 2. The coating amount (g / m ² ) of each compound in the image forming layer at this time is the same as that in the photothermographic material-1.

  The chemical structures of the compounds used in the examples of the present invention are shown below.

4). Evaluation of photographic performance 1) Preparation The obtained sample was cut into half-cut size (43 cm length x 35 cm width), packaged in the following packaging materials in an environment of 25 ° C. and 50% RH, and stored at room temperature for 2 weeks. The following evaluation was performed.
<Packaging materials>
Laminate film in which PET 10 μm / PE 12 μm / aluminum foil 9 μm / Ny 15 μm / polyethylene 50 μm containing 3% by mass of carbon is laminated:
Oxygen permeability: 0.02 mL / atm · m ² · 25 ° C · day,
Moisture permeability: 0.10 g / atm · m ² · 25 ° C · day

2) Exposure / development of photothermographic material The photothermographic materials-1 to 15 are exposed and thermally developed with a dry laser imager DRYPIX7000 (equipped with a 660 nm semiconductor laser with a maximum output of 50 mW (IIIB)). A total of 14 seconds with three panel heaters set at 107 ° C.-121 ° C.-121 ° C.), and the obtained image was evaluated with a densitometer. The photosensitive material transport speed during thermal development is
It was 28 mm / sec.

3) Evaluation of photographic performance <Evaluation of raw preservation>
Each sample was stored for an additional 7 days under conditions of 25 ° C.-40% RH and 40 ° C.-70% RH or 50 ° C.-70% RH, and then exposed and developed by the above-described method in an environment of 25 ° C.-55% RH. An image was obtained. The conditions of 40 ° C.-70% RH and 50 ° C.-70% RH are compulsory conditions for evaluating the storage stability of the photothermographic material until it is subjected to exposure and development. Table 2 shows (A) when measured after storage at 40 ° C.-70% RH and (B) when measured after storage at 50 ° C.-70% RH.
As an evaluation of raw storage stability, changes in the minimum concentration (Dmin) were measured. With respect to Dmin of the sample stored at 25 ° C.-40% RH, the increase rate (%) (ΔDmin (A)) of Dmin of the sample stored at 40 ° C.-70% RH and at 50 ° C.-70% RH Table 2 shows the increase rate (%) (ΔDmin (B)) of Dmin of the stored samples.

<Evaluation of image preservation>
The photothermographic material that had been exposed and heat-developed was sufficiently exposed to light, conditioned at 25 ° C.-70% RH for 3 hours, sealed in a light-shielding bag, and left in a 60 ° C. environment for 24 hours. At this time, the change rate of the minimum concentration was evaluated by the minimum concentration increase rate (%) (ΔDmin) with the sample left for 24 hours in an environment of 25 ° C.-40% RH. The smaller the ΔDmin, the better the image storage stability.

  The evaluation results are shown in Table 2.

As shown in Table 2, a non-photosensitive intermediate layer A and a non-photosensitive intermediate layer B are provided between the image forming layer and the outermost layer, and the non-photosensitive intermediate layer provided adjacent to the image forming layer. The binder of layer A contains 80% by mass or more of a polymer latex obtained by copolymerizing the monomer represented by the general formula (M), and at least one binder of the outermost layer and the non-photosensitive intermediate layer B is animal-based. When the hydrophilic polymer derived from protein is contained in an amount of 50% by mass or more, the photothermographic material is excellent in raw storability and image storability.
In particular, when latex is contained in the outermost layer, the photothermographic material is excellent in storage stability without causing image quality deterioration due to stickiness or finger marks.

Example 2
1. Preparation of coated sample (preparation of organic silver salt dispersions B to C)
In the preparation of the organic silver salt dispersion A of Example 1, except that the ratio of recrystallized behenic acid A and recrystallized stearic acid was changed, the organic silver salt dispersions B to B having different silver behenate contents were similarly used. C was prepared.

(Preparation of reducing agent-2 dispersion)
To 10 g of reducing agent-2, 4 g of hydroxypropylcellulose and 86 g of water were added and stirred well and left as a slurry for 10 hours. Thereafter, 168 g of zirconia beads having an average diameter of 0.5 mm were prepared, put into a vessel together with the slurry, and dispersed for 10 hours using the same disperser used for the preparation of the organic acid silver microcrystal dispersion. A liquid was obtained. As for the average particle size, 70% by mass was 1.0 μm or less.

(Preparation of image forming layer coating liquids 2 to 4)
In the preparation of the image forming layer coating liquid-1 of Example 1, the organic silver salt dispersion, the reducing agent, the organic polyhalogen compound, the hydrogen bonding compound, the color tone adjusting agent and the development accelerator were changed as shown in Table 3. The image forming layer coating solutions 2 to 4 were prepared in the same manner except that.

(Preparation of photothermographic material-201 to 203)
In the production of the photothermographic material-6 of Example 1, the photothermographic material-201 was prepared in the same manner except that the image forming layer coating solution-1 was changed to any one of the image forming layer coating solutions-2-4. 203 was produced. The coating amount (g / m ² ) of each compound in the image forming layer at this time is the same as that in the photothermographic material-6.

2. Performance Evaluation The obtained photothermographic materials -201 to 203 were exposed and developed in the same manner as in Example 1 for evaluation. The results are shown in Table 3.

  Even in the photothermographic material suitable for rapid processing as in Example 2, the non-photosensitive intermediate layer A and the non-photosensitive intermediate layer B are provided between the image forming layer and the outermost layer, and the image The binder of the non-photosensitive intermediate layer A provided adjacent to the forming layer contains 80% by mass or more of a latex of a polymer obtained by copolymerizing the monomer represented by the general formula (M), and the outermost layer and the non-photosensitive layer If the binder of at least one layer of the intermediate layer B is a light-sensitive material containing 50% by mass or more of a hydrophilic polymer derived from animal protein, the raw storability and the image storability were extremely excellent.

Example 3
In the intermediate layer A coating liquid-2 of Example 1, 100 g of the crosslinking agent-1 (Epocross K-2020E (Nippon Shokubai Co., Ltd.)) shown in Table 4 was further added to prepare the intermediate layer A coating liquid-6. did. A photothermographic material 301 was prepared in the same manner as the photothermographic material-2 of Example 1 except that this intermediate layer coating solution was used. Furthermore, evaluation was performed in the same manner as in Example 1. The results are shown in Table 4.

  By adding a cross-linking agent, raw storability and image storability were further improved.

1 is a schematic configuration diagram of a heat development recording apparatus equipped with a laser recording apparatus according to the present invention. It is a block diagram which shows schematic structure of the conveyance part for conveying the sheet-like heat development recording material in a laser recording apparatus, and a scanning exposure part.

Explanation of symbols

3 Photothermographic recording materials 10a, 10b, 10c Photosensitive material trays 13a, 13b, 13c Single wafer conveying rollers 15a, 15b, 15c Photosensitive material 16 Upper light shielding cover 17 Sub-scanning conveying unit (sub-scanning means)
19 Scanning exposure unit (laser irradiation means)
21 and 22 Driving roller 23 Guide plate 25 and 26 Slope portion 29 Pressing portion 31 Guide plate 35 Semiconductor laser 37 Drive circuit 39 Intensity modulator 41 Polygon mirror 43 Condensing lens 45 Mirror 51a, 51b and 51c Heat developing plate 52 Driving roller 53 Reduction gear 55 Conveying roller 57 Cooling rotor 59 Cooling rotor 61 Cooling plate 63 Discharge roller 100 Laser recording device 150 Thermal development recording device

Claims (21)

A photothermographic material comprising an image forming layer containing at least a photosensitive silver halide, a non-photosensitive organic acid silver salt, a reducing agent, and a binder on at least one surface side of a support,
In the surface on which the image forming layer is provided on the support, an outermost layer is provided on the side farthest from the support,
A non-photosensitive intermediate layer A is provided between the image forming layer and the outermost layer adjacent to the image forming layer, and the binder of the non-photosensitive intermediate layer A is represented by the following general formula (M) Containing 80% by mass or more of a copolymer obtained by copolymerizing the monomer represented by
A non-photosensitive intermediate layer B is provided between the non-photosensitive intermediate layer A and the outermost layer,
The photothermographic material, wherein 50% by mass or more of at least one binder of the outermost layer and the non-photosensitive intermediate layer B is a hydrophilic polymer derived from animal protein:
Formula ^{_{(M) CH 2 = CR 01}} -CR 02 = CH 2
(Wherein R ⁰¹ and R ⁰² represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a halogen atom or a cyano group).   The polymer obtained by copolymerizing the monomer represented by the general formula (M) is a polymer obtained by copolymerizing the monomer represented by the general formula (M) at 10% by mass or more and 70% by mass or less. The photothermographic material according to claim 1.   The polymer obtained by copolymerizing the monomer represented by the general formula (M) is a polymer obtained by copolymerizing the monomer represented by the general formula (M) at 20% by mass or more and 40% by mass or less. The photothermographic material according to claim 1 or 2.   2. The binder of the non-photosensitive intermediate layer B contains 50% by mass or more of a hydrophilic polymer derived from animal protein, and the binder of the outermost layer contains a latex of a hydrophobic polymer. The photothermographic material according to claim 1.   The non-photosensitive intermediate layer B is composed of two or more layers, and the non-photosensitive intermediate layer B on the side close to the non-photosensitive intermediate layer A contains 50% by mass or more of a hydrophilic polymer not derived from animal protein. The non-photosensitive intermediate layer B on the side closest to the outermost layer contains a binder containing 50% by mass or more of a hydrophilic polymer derived from animal protein. 2. The photothermographic material according to item 1.   6. The photothermographic material according to claim 5, wherein the outermost layer binder contains a hydrophilic polymer derived from animal protein.   6. The photothermographic material according to claim 5, wherein the outermost binder contains a latex of a hydrophobic polymer.   6. The photothermographic material according to claim 5, wherein the outermost binder contains a hydrophilic polymer derived from animal protein and a latex of a hydrophobic polymer. The photothermographic material according to claim 1, wherein the reducing agent is a compound represented by the following general formula (R1):

(In the formula, R ¹¹ and R ¹¹ ′ each independently represent a secondary or tertiary alkyl group having 1 to 15 carbon atoms. R ¹² and R ¹² ′ are each independently substituted with a hydrogen atom or a benzene ring. .L representing the possible substituents, -S- group, or -CHR ¹³ - .R ¹³ representing the group, .X ¹ and X ¹ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms' is Each independently represents a hydrogen atom or a group capable of substituting for a benzene ring).   The photothermographic material according to claim 1, wherein the image forming layer further contains a development accelerator. The photothermographic material according to claim 9 or 10, wherein the image forming layer further contains a compound represented by the following general formula (D):
It is.

(Wherein R ²¹ to R ²³ each independently represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, or a heterocyclic group). The photothermographic material according to claim 1, wherein the image forming layer further contains a compound represented by the following general formula (H).
General formula (H)
Q- (Y) n-C (Z ₁ ) (Z ₂ ) X
In the formula, Q represents an alkyl group, an aryl group, or a heterocyclic group. Y represents a divalent linking group. n represents 0-1. Z ₁ and Z ₂ each independently represent a halogen atom. X represents a hydrogen atom or an electron withdrawing group.   13. The photothermographic material according to claim 12, wherein the image forming layer contains two or more compounds represented by the general formula (H). The photothermographic material according to claim 1, wherein the image forming layer further contains a compound represented by the following general formula (I):

(In the formula (I), R represents a substituent. M represents an integer of 1 to 6.)   The photothermographic material according to claim 14, wherein the image forming layer further contains a color tone adjusting agent.   The photothermographic material according to claim 1, wherein the non-photosensitive organic acid silver salt contains 90 mol% or more of silver behenate. The photothermographic material according to claim 1, wherein the coated silver amount is 1.3 g / m ² or less.   18. The photothermographic sensor according to claim 1, wherein any layer on the surface side on which the image forming layer is provided with respect to the support contains a crosslinking agent. material. An image forming method of a photothermographic material having an image exposure step and a heat development step,
19. The photothermographic material image forming method according to claim 1, wherein the photothermographic material according to claim 1 is heated in 16 seconds or less in the heat development step. An image forming method of a photothermographic material having an image exposure step and a heat development step,
In the said heat development process, the photothermographic material of any one of Claims 1-18 is conveyed at a speed | rate of 23 mm / sec or more, The image forming method of the photothermographic material characterized by the above-mentioned. . The photothermographic material according to any one of claims 1 to 18, wherein the photothermographic material according to any one of claims 1 to 18 is conveyed at a speed of 23 mm / sec or more in the heat development step. Image forming method for photosensitive material.

Images